1 /*
2 * Copyright (c) 1998, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "ci/ciMethodData.hpp"
27 #include "compiler/compileLog.hpp"
28 #include "gc/shared/barrierSet.hpp"
29 #include "gc/shared/c2/barrierSetC2.hpp"
30 #include "libadt/vectset.hpp"
31 #include "memory/allocation.inline.hpp"
32 #include "memory/resourceArea.hpp"
33 #include "opto/addnode.hpp"
34 #include "opto/callnode.hpp"
35 #include "opto/connode.hpp"
36 #include "opto/convertnode.hpp"
37 #include "opto/divnode.hpp"
38 #include "opto/idealGraphPrinter.hpp"
39 #include "opto/loopnode.hpp"
40 #include "opto/mulnode.hpp"
41 #include "opto/rootnode.hpp"
42 #include "opto/superword.hpp"
43
44 //=============================================================================
45 //------------------------------is_loop_iv-------------------------------------
46 // Determine if a node is Counted loop induction variable.
47 // The method is declared in node.hpp.
48 const Node* Node::is_loop_iv() const {
49 if (this->is_Phi() && !this->as_Phi()->is_copy() &&
50 this->as_Phi()->region()->is_CountedLoop() &&
51 this->as_Phi()->region()->as_CountedLoop()->phi() == this) {
52 return this;
53 } else {
54 return NULL;
55 }
56 }
57
58 //=============================================================================
59 //------------------------------dump_spec--------------------------------------
60 // Dump special per-node info
61 #ifndef PRODUCT
62 void LoopNode::dump_spec(outputStream *st) const {
63 if (is_inner_loop()) st->print( "inner " );
64 if (is_partial_peel_loop()) st->print( "partial_peel " );
65 if (partial_peel_has_failed()) st->print( "partial_peel_failed " );
66 }
67 #endif
68
69 //------------------------------is_valid_counted_loop-------------------------
70 bool LoopNode::is_valid_counted_loop() const {
71 if (is_CountedLoop()) {
72 CountedLoopNode* l = as_CountedLoop();
73 CountedLoopEndNode* le = l->loopexit_or_null();
74 if (le != NULL &&
75 le->proj_out_or_null(1 /* true */) == l->in(LoopNode::LoopBackControl)) {
76 Node* phi = l->phi();
77 Node* exit = le->proj_out_or_null(0 /* false */);
78 if (exit != NULL && exit->Opcode() == Op_IfFalse &&
79 phi != NULL && phi->is_Phi() &&
80 phi->in(LoopNode::LoopBackControl) == l->incr() &&
81 le->loopnode() == l && le->stride_is_con()) {
82 return true;
83 }
84 }
85 }
86 return false;
87 }
88
89 //------------------------------get_early_ctrl---------------------------------
90 // Compute earliest legal control
91 Node *PhaseIdealLoop::get_early_ctrl( Node *n ) {
92 assert( !n->is_Phi() && !n->is_CFG(), "this code only handles data nodes" );
93 uint i;
94 Node *early;
95 if (n->in(0) && !n->is_expensive()) {
96 early = n->in(0);
97 if (!early->is_CFG()) // Might be a non-CFG multi-def
98 early = get_ctrl(early); // So treat input as a straight data input
99 i = 1;
100 } else {
101 early = get_ctrl(n->in(1));
102 i = 2;
103 }
104 uint e_d = dom_depth(early);
105 assert( early, "" );
106 for (; i < n->req(); i++) {
107 Node *cin = get_ctrl(n->in(i));
108 assert( cin, "" );
109 // Keep deepest dominator depth
110 uint c_d = dom_depth(cin);
111 if (c_d > e_d) { // Deeper guy?
112 early = cin; // Keep deepest found so far
113 e_d = c_d;
114 } else if (c_d == e_d && // Same depth?
115 early != cin) { // If not equal, must use slower algorithm
116 // If same depth but not equal, one _must_ dominate the other
117 // and we want the deeper (i.e., dominated) guy.
118 Node *n1 = early;
119 Node *n2 = cin;
120 while (1) {
121 n1 = idom(n1); // Walk up until break cycle
122 n2 = idom(n2);
123 if (n1 == cin || // Walked early up to cin
124 dom_depth(n2) < c_d)
125 break; // early is deeper; keep him
126 if (n2 == early || // Walked cin up to early
127 dom_depth(n1) < c_d) {
128 early = cin; // cin is deeper; keep him
129 break;
130 }
131 }
132 e_d = dom_depth(early); // Reset depth register cache
133 }
134 }
135
136 // Return earliest legal location
137 assert(early == find_non_split_ctrl(early), "unexpected early control");
138
139 if (n->is_expensive() && !_verify_only && !_verify_me) {
140 assert(n->in(0), "should have control input");
141 early = get_early_ctrl_for_expensive(n, early);
142 }
143
144 return early;
145 }
146
147 //------------------------------get_early_ctrl_for_expensive---------------------------------
148 // Move node up the dominator tree as high as legal while still beneficial
149 Node *PhaseIdealLoop::get_early_ctrl_for_expensive(Node *n, Node* earliest) {
150 assert(n->in(0) && n->is_expensive(), "expensive node with control input here");
151 assert(OptimizeExpensiveOps, "optimization off?");
152
153 Node* ctl = n->in(0);
154 assert(ctl->is_CFG(), "expensive input 0 must be cfg");
155 uint min_dom_depth = dom_depth(earliest);
156 #ifdef ASSERT
157 if (!is_dominator(ctl, earliest) && !is_dominator(earliest, ctl)) {
158 dump_bad_graph("Bad graph detected in get_early_ctrl_for_expensive", n, earliest, ctl);
159 assert(false, "Bad graph detected in get_early_ctrl_for_expensive");
160 }
161 #endif
162 if (dom_depth(ctl) < min_dom_depth) {
163 return earliest;
164 }
165
166 while (1) {
167 Node *next = ctl;
168 // Moving the node out of a loop on the projection of a If
169 // confuses loop predication. So once we hit a Loop in a If branch
170 // that doesn't branch to an UNC, we stop. The code that process
171 // expensive nodes will notice the loop and skip over it to try to
172 // move the node further up.
173 if (ctl->is_CountedLoop() && ctl->in(1) != NULL && ctl->in(1)->in(0) != NULL && ctl->in(1)->in(0)->is_If()) {
174 if (!ctl->in(1)->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
175 break;
176 }
177 next = idom(ctl->in(1)->in(0));
178 } else if (ctl->is_Proj()) {
179 // We only move it up along a projection if the projection is
180 // the single control projection for its parent: same code path,
181 // if it's a If with UNC or fallthrough of a call.
182 Node* parent_ctl = ctl->in(0);
183 if (parent_ctl == NULL) {
184 break;
185 } else if (parent_ctl->is_CountedLoopEnd() && parent_ctl->as_CountedLoopEnd()->loopnode() != NULL) {
186 next = parent_ctl->as_CountedLoopEnd()->loopnode()->init_control();
187 } else if (parent_ctl->is_If()) {
188 if (!ctl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none)) {
189 break;
190 }
191 assert(idom(ctl) == parent_ctl, "strange");
192 next = idom(parent_ctl);
193 } else if (ctl->is_CatchProj()) {
194 if (ctl->as_Proj()->_con != CatchProjNode::fall_through_index) {
195 break;
196 }
197 assert(parent_ctl->in(0)->in(0)->is_Call(), "strange graph");
198 next = parent_ctl->in(0)->in(0)->in(0);
199 } else {
200 // Check if parent control has a single projection (this
201 // control is the only possible successor of the parent
202 // control). If so, we can try to move the node above the
203 // parent control.
204 int nb_ctl_proj = 0;
205 for (DUIterator_Fast imax, i = parent_ctl->fast_outs(imax); i < imax; i++) {
206 Node *p = parent_ctl->fast_out(i);
207 if (p->is_Proj() && p->is_CFG()) {
208 nb_ctl_proj++;
209 if (nb_ctl_proj > 1) {
210 break;
211 }
212 }
213 }
214
215 if (nb_ctl_proj > 1) {
216 break;
217 }
218 assert(parent_ctl->is_Start() || parent_ctl->is_MemBar() || parent_ctl->is_Call() ||
219 BarrierSet::barrier_set()->barrier_set_c2()->is_gc_barrier_node(parent_ctl), "unexpected node");
220 assert(idom(ctl) == parent_ctl, "strange");
221 next = idom(parent_ctl);
222 }
223 } else {
224 next = idom(ctl);
225 }
226 if (next->is_Root() || next->is_Start() || dom_depth(next) < min_dom_depth) {
227 break;
228 }
229 ctl = next;
230 }
231
232 if (ctl != n->in(0)) {
233 _igvn.replace_input_of(n, 0, ctl);
234 _igvn.hash_insert(n);
235 }
236
237 return ctl;
238 }
239
240
241 //------------------------------set_early_ctrl---------------------------------
242 // Set earliest legal control
243 void PhaseIdealLoop::set_early_ctrl( Node *n ) {
244 Node *early = get_early_ctrl(n);
245
246 // Record earliest legal location
247 set_ctrl(n, early);
248 }
249
250 //------------------------------set_subtree_ctrl-------------------------------
251 // set missing _ctrl entries on new nodes
252 void PhaseIdealLoop::set_subtree_ctrl( Node *n ) {
253 // Already set? Get out.
254 if( _nodes[n->_idx] ) return;
255 // Recursively set _nodes array to indicate where the Node goes
256 uint i;
257 for( i = 0; i < n->req(); ++i ) {
258 Node *m = n->in(i);
259 if( m && m != C->root() )
260 set_subtree_ctrl( m );
261 }
262
263 // Fixup self
264 set_early_ctrl( n );
265 }
266
267 // Create a skeleton strip mined outer loop: a Loop head before the
268 // inner strip mined loop, a safepoint and an exit condition guarded
269 // by an opaque node after the inner strip mined loop with a backedge
270 // to the loop head. The inner strip mined loop is left as it is. Only
271 // once loop optimizations are over, do we adjust the inner loop exit
272 // condition to limit its number of iterations, set the outer loop
273 // exit condition and add Phis to the outer loop head. Some loop
274 // optimizations that operate on the inner strip mined loop need to be
275 // aware of the outer strip mined loop: loop unswitching needs to
276 // clone the outer loop as well as the inner, unrolling needs to only
277 // clone the inner loop etc. No optimizations need to change the outer
278 // strip mined loop as it is only a skeleton.
279 IdealLoopTree* PhaseIdealLoop::create_outer_strip_mined_loop(BoolNode *test, Node *cmp, Node *init_control,
280 IdealLoopTree* loop, float cl_prob, float le_fcnt,
281 Node*& entry_control, Node*& iffalse) {
282 Node* outer_test = _igvn.intcon(0);
283 set_ctrl(outer_test, C->root());
284 Node *orig = iffalse;
285 iffalse = iffalse->clone();
286 _igvn.register_new_node_with_optimizer(iffalse);
287 set_idom(iffalse, idom(orig), dom_depth(orig));
288
289 IfNode *outer_le = new OuterStripMinedLoopEndNode(iffalse, outer_test, cl_prob, le_fcnt);
290 Node *outer_ift = new IfTrueNode (outer_le);
291 Node* outer_iff = orig;
292 _igvn.replace_input_of(outer_iff, 0, outer_le);
293
294 LoopNode *outer_l = new OuterStripMinedLoopNode(C, init_control, outer_ift);
295 entry_control = outer_l;
296
297 IdealLoopTree* outer_ilt = new IdealLoopTree(this, outer_l, outer_ift);
298 IdealLoopTree* parent = loop->_parent;
299 IdealLoopTree* sibling = parent->_child;
300 if (sibling == loop) {
301 parent->_child = outer_ilt;
302 } else {
303 while (sibling->_next != loop) {
304 sibling = sibling->_next;
305 }
306 sibling->_next = outer_ilt;
307 }
308 outer_ilt->_next = loop->_next;
309 outer_ilt->_parent = parent;
310 outer_ilt->_child = loop;
311 outer_ilt->_nest = loop->_nest;
312 loop->_parent = outer_ilt;
313 loop->_next = NULL;
314 loop->_nest++;
315
316 set_loop(iffalse, outer_ilt);
317 register_control(outer_le, outer_ilt, iffalse);
318 register_control(outer_ift, outer_ilt, outer_le);
319 set_idom(outer_iff, outer_le, dom_depth(outer_le));
320 _igvn.register_new_node_with_optimizer(outer_l);
321 set_loop(outer_l, outer_ilt);
322 set_idom(outer_l, init_control, dom_depth(init_control)+1);
323
324 return outer_ilt;
325 }
326
327 //------------------------------is_counted_loop--------------------------------
328 bool PhaseIdealLoop::is_counted_loop(Node* x, IdealLoopTree*& loop) {
329 PhaseGVN *gvn = &_igvn;
330
331 // Counted loop head must be a good RegionNode with only 3 not NULL
332 // control input edges: Self, Entry, LoopBack.
333 if (x->in(LoopNode::Self) == NULL || x->req() != 3 || loop->_irreducible) {
334 return false;
335 }
336 Node *init_control = x->in(LoopNode::EntryControl);
337 Node *back_control = x->in(LoopNode::LoopBackControl);
338 if (init_control == NULL || back_control == NULL) // Partially dead
339 return false;
340 // Must also check for TOP when looking for a dead loop
341 if (init_control->is_top() || back_control->is_top())
342 return false;
343
344 // Allow funny placement of Safepoint
345 if (back_control->Opcode() == Op_SafePoint) {
346 if (LoopStripMiningIter != 0) {
347 // Leaving the safepoint on the backedge and creating a
348 // CountedLoop will confuse optimizations. We can't move the
349 // safepoint around because its jvm state wouldn't match a new
350 // location. Give up on that loop.
351 return false;
352 }
353 back_control = back_control->in(TypeFunc::Control);
354 }
355
356 // Controlling test for loop
357 Node *iftrue = back_control;
358 uint iftrue_op = iftrue->Opcode();
359 if (iftrue_op != Op_IfTrue &&
360 iftrue_op != Op_IfFalse)
361 // I have a weird back-control. Probably the loop-exit test is in
362 // the middle of the loop and I am looking at some trailing control-flow
363 // merge point. To fix this I would have to partially peel the loop.
364 return false; // Obscure back-control
365
366 // Get boolean guarding loop-back test
367 Node *iff = iftrue->in(0);
368 if (get_loop(iff) != loop || !iff->in(1)->is_Bool())
369 return false;
370 BoolNode *test = iff->in(1)->as_Bool();
371 BoolTest::mask bt = test->_test._test;
372 float cl_prob = iff->as_If()->_prob;
373 if (iftrue_op == Op_IfFalse) {
374 bt = BoolTest(bt).negate();
375 cl_prob = 1.0 - cl_prob;
376 }
377 // Get backedge compare
378 Node *cmp = test->in(1);
379 int cmp_op = cmp->Opcode();
380 if (cmp_op != Op_CmpI)
381 return false; // Avoid pointer & float compares
382
383 // Find the trip-counter increment & limit. Limit must be loop invariant.
384 Node *incr = cmp->in(1);
385 Node *limit = cmp->in(2);
386
387 // ---------
388 // need 'loop()' test to tell if limit is loop invariant
389 // ---------
390
391 if (!is_member(loop, get_ctrl(incr))) { // Swapped trip counter and limit?
392 Node *tmp = incr; // Then reverse order into the CmpI
393 incr = limit;
394 limit = tmp;
395 bt = BoolTest(bt).commute(); // And commute the exit test
396 }
397 if (is_member(loop, get_ctrl(limit))) // Limit must be loop-invariant
398 return false;
399 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
400 return false;
401
402 Node* phi_incr = NULL;
403 // Trip-counter increment must be commutative & associative.
404 if (incr->Opcode() == Op_CastII) {
405 incr = incr->in(1);
406 }
407 if (incr->is_Phi()) {
408 if (incr->as_Phi()->region() != x || incr->req() != 3)
409 return false; // Not simple trip counter expression
410 phi_incr = incr;
411 incr = phi_incr->in(LoopNode::LoopBackControl); // Assume incr is on backedge of Phi
412 if (!is_member(loop, get_ctrl(incr))) // Trip counter must be loop-variant
413 return false;
414 }
415
416 Node* trunc1 = NULL;
417 Node* trunc2 = NULL;
418 const TypeInt* iv_trunc_t = NULL;
419 Node* orig_incr = incr;
420 if (!(incr = CountedLoopNode::match_incr_with_optional_truncation(incr, &trunc1, &trunc2, &iv_trunc_t))) {
421 return false; // Funny increment opcode
422 }
423 assert(incr->Opcode() == Op_AddI, "wrong increment code");
424
425 const TypeInt* limit_t = gvn->type(limit)->is_int();
426 if (trunc1 != NULL) {
427 // When there is a truncation, we must be sure that after the truncation
428 // the trip counter will end up higher than the limit, otherwise we are looking
429 // at an endless loop. Can happen with range checks.
430
431 // Example:
432 // int i = 0;
433 // while (true)
434 // sum + = array[i];
435 // i++;
436 // i = i && 0x7fff;
437 // }
438 //
439 // If the array is shorter than 0x8000 this exits through a AIOOB
440 // - Counted loop transformation is ok
441 // If the array is longer then this is an endless loop
442 // - No transformation can be done.
443
444 const TypeInt* incr_t = gvn->type(orig_incr)->is_int();
445 if (limit_t->_hi > incr_t->_hi) {
446 // if the limit can have a higher value than the increment (before the phi)
447 return false;
448 }
449 }
450
451 // Get merge point
452 Node *xphi = incr->in(1);
453 Node *stride = incr->in(2);
454 if (!stride->is_Con()) { // Oops, swap these
455 if (!xphi->is_Con()) // Is the other guy a constant?
456 return false; // Nope, unknown stride, bail out
457 Node *tmp = xphi; // 'incr' is commutative, so ok to swap
458 xphi = stride;
459 stride = tmp;
460 }
461 if (xphi->Opcode() == Op_CastII) {
462 xphi = xphi->in(1);
463 }
464 // Stride must be constant
465 int stride_con = stride->get_int();
466 if (stride_con == 0)
467 return false; // missed some peephole opt
468
469 if (!xphi->is_Phi())
470 return false; // Too much math on the trip counter
471 if (phi_incr != NULL && phi_incr != xphi)
472 return false;
473 PhiNode *phi = xphi->as_Phi();
474
475 // Phi must be of loop header; backedge must wrap to increment
476 if (phi->region() != x)
477 return false;
478 if ((trunc1 == NULL && phi->in(LoopNode::LoopBackControl) != incr) ||
479 (trunc1 != NULL && phi->in(LoopNode::LoopBackControl) != trunc1)) {
480 return false;
481 }
482 Node *init_trip = phi->in(LoopNode::EntryControl);
483
484 // If iv trunc type is smaller than int, check for possible wrap.
485 if (!TypeInt::INT->higher_equal(iv_trunc_t)) {
486 assert(trunc1 != NULL, "must have found some truncation");
487
488 // Get a better type for the phi (filtered thru if's)
489 const TypeInt* phi_ft = filtered_type(phi);
490
491 // Can iv take on a value that will wrap?
492 //
493 // Ensure iv's limit is not within "stride" of the wrap value.
494 //
495 // Example for "short" type
496 // Truncation ensures value is in the range -32768..32767 (iv_trunc_t)
497 // If the stride is +10, then the last value of the induction
498 // variable before the increment (phi_ft->_hi) must be
499 // <= 32767 - 10 and (phi_ft->_lo) must be >= -32768 to
500 // ensure no truncation occurs after the increment.
501
502 if (stride_con > 0) {
503 if (iv_trunc_t->_hi - phi_ft->_hi < stride_con ||
504 iv_trunc_t->_lo > phi_ft->_lo) {
505 return false; // truncation may occur
506 }
507 } else if (stride_con < 0) {
508 if (iv_trunc_t->_lo - phi_ft->_lo > stride_con ||
509 iv_trunc_t->_hi < phi_ft->_hi) {
510 return false; // truncation may occur
511 }
512 }
513 // No possibility of wrap so truncation can be discarded
514 // Promote iv type to Int
515 } else {
516 assert(trunc1 == NULL && trunc2 == NULL, "no truncation for int");
517 }
518
519 // If the condition is inverted and we will be rolling
520 // through MININT to MAXINT, then bail out.
521 if (bt == BoolTest::eq || // Bail out, but this loop trips at most twice!
522 // Odd stride
523 (bt == BoolTest::ne && stride_con != 1 && stride_con != -1) ||
524 // Count down loop rolls through MAXINT
525 ((bt == BoolTest::le || bt == BoolTest::lt) && stride_con < 0) ||
526 // Count up loop rolls through MININT
527 ((bt == BoolTest::ge || bt == BoolTest::gt) && stride_con > 0)) {
528 return false; // Bail out
529 }
530
531 const TypeInt* init_t = gvn->type(init_trip)->is_int();
532
533 if (stride_con > 0) {
534 jlong init_p = (jlong)init_t->_lo + stride_con;
535 if (init_p > (jlong)max_jint || init_p > (jlong)limit_t->_hi)
536 return false; // cyclic loop or this loop trips only once
537 } else {
538 jlong init_p = (jlong)init_t->_hi + stride_con;
539 if (init_p < (jlong)min_jint || init_p < (jlong)limit_t->_lo)
540 return false; // cyclic loop or this loop trips only once
541 }
542
543 if (phi_incr != NULL) {
544 // check if there is a possiblity of IV overflowing after the first increment
545 if (stride_con > 0) {
546 if (init_t->_hi > max_jint - stride_con) {
547 return false;
548 }
549 } else {
550 if (init_t->_lo < min_jint - stride_con) {
551 return false;
552 }
553 }
554 }
555
556 // =================================================
557 // ---- SUCCESS! Found A Trip-Counted Loop! -----
558 //
559 assert(x->Opcode() == Op_Loop, "regular loops only");
560 C->print_method(PHASE_BEFORE_CLOOPS, 3);
561
562 Node *hook = new Node(6);
563
564 // ===================================================
565 // Generate loop limit check to avoid integer overflow
566 // in cases like next (cyclic loops):
567 //
568 // for (i=0; i <= max_jint; i++) {}
569 // for (i=0; i < max_jint; i+=2) {}
570 //
571 //
572 // Limit check predicate depends on the loop test:
573 //
574 // for(;i != limit; i++) --> limit <= (max_jint)
575 // for(;i < limit; i+=stride) --> limit <= (max_jint - stride + 1)
576 // for(;i <= limit; i+=stride) --> limit <= (max_jint - stride )
577 //
578
579 // Check if limit is excluded to do more precise int overflow check.
580 bool incl_limit = (bt == BoolTest::le || bt == BoolTest::ge);
581 int stride_m = stride_con - (incl_limit ? 0 : (stride_con > 0 ? 1 : -1));
582
583 // If compare points directly to the phi we need to adjust
584 // the compare so that it points to the incr. Limit have
585 // to be adjusted to keep trip count the same and the
586 // adjusted limit should be checked for int overflow.
587 if (phi_incr != NULL) {
588 stride_m += stride_con;
589 }
590
591 if (limit->is_Con()) {
592 int limit_con = limit->get_int();
593 if ((stride_con > 0 && limit_con > (max_jint - stride_m)) ||
594 (stride_con < 0 && limit_con < (min_jint - stride_m))) {
595 // Bailout: it could be integer overflow.
596 return false;
597 }
598 } else if ((stride_con > 0 && limit_t->_hi <= (max_jint - stride_m)) ||
599 (stride_con < 0 && limit_t->_lo >= (min_jint - stride_m))) {
600 // Limit's type may satisfy the condition, for example,
601 // when it is an array length.
602 } else {
603 // Generate loop's limit check.
604 // Loop limit check predicate should be near the loop.
605 ProjNode *limit_check_proj = find_predicate_insertion_point(init_control, Deoptimization::Reason_loop_limit_check);
606 if (!limit_check_proj) {
607 // The limit check predicate is not generated if this method trapped here before.
608 #ifdef ASSERT
609 if (TraceLoopLimitCheck) {
610 tty->print("missing loop limit check:");
611 loop->dump_head();
612 x->dump(1);
613 }
614 #endif
615 return false;
616 }
617
618 IfNode* check_iff = limit_check_proj->in(0)->as_If();
619
620 if (!is_dominator(get_ctrl(limit), check_iff->in(0))) {
621 return false;
622 }
623
624 Node* cmp_limit;
625 Node* bol;
626
627 if (stride_con > 0) {
628 cmp_limit = new CmpINode(limit, _igvn.intcon(max_jint - stride_m));
629 bol = new BoolNode(cmp_limit, BoolTest::le);
630 } else {
631 cmp_limit = new CmpINode(limit, _igvn.intcon(min_jint - stride_m));
632 bol = new BoolNode(cmp_limit, BoolTest::ge);
633 }
634 cmp_limit = _igvn.register_new_node_with_optimizer(cmp_limit);
635 bol = _igvn.register_new_node_with_optimizer(bol);
636 set_subtree_ctrl(bol);
637
638 // Replace condition in original predicate but preserve Opaque node
639 // so that previous predicates could be found.
640 assert(check_iff->in(1)->Opcode() == Op_Conv2B &&
641 check_iff->in(1)->in(1)->Opcode() == Op_Opaque1, "");
642 Node* opq = check_iff->in(1)->in(1);
643 _igvn.replace_input_of(opq, 1, bol);
644 // Update ctrl.
645 set_ctrl(opq, check_iff->in(0));
646 set_ctrl(check_iff->in(1), check_iff->in(0));
647
648 #ifndef PRODUCT
649 // report that the loop predication has been actually performed
650 // for this loop
651 if (TraceLoopLimitCheck) {
652 tty->print_cr("Counted Loop Limit Check generated:");
653 debug_only( bol->dump(2); )
654 }
655 #endif
656 }
657
658 if (phi_incr != NULL) {
659 // If compare points directly to the phi we need to adjust
660 // the compare so that it points to the incr. Limit have
661 // to be adjusted to keep trip count the same and we
662 // should avoid int overflow.
663 //
664 // i = init; do {} while(i++ < limit);
665 // is converted to
666 // i = init; do {} while(++i < limit+1);
667 //
668 limit = gvn->transform(new AddINode(limit, stride));
669 }
670
671 // Now we need to canonicalize loop condition.
672 if (bt == BoolTest::ne) {
673 assert(stride_con == 1 || stride_con == -1, "simple increment only");
674 // 'ne' can be replaced with 'lt' only when init < limit.
675 if (stride_con > 0 && init_t->_hi < limit_t->_lo)
676 bt = BoolTest::lt;
677 // 'ne' can be replaced with 'gt' only when init > limit.
678 if (stride_con < 0 && init_t->_lo > limit_t->_hi)
679 bt = BoolTest::gt;
680 }
681
682 if (incl_limit) {
683 // The limit check guaranties that 'limit <= (max_jint - stride)' so
684 // we can convert 'i <= limit' to 'i < limit+1' since stride != 0.
685 //
686 Node* one = (stride_con > 0) ? gvn->intcon( 1) : gvn->intcon(-1);
687 limit = gvn->transform(new AddINode(limit, one));
688 if (bt == BoolTest::le)
689 bt = BoolTest::lt;
690 else if (bt == BoolTest::ge)
691 bt = BoolTest::gt;
692 else
693 ShouldNotReachHere();
694 }
695 set_subtree_ctrl( limit );
696
697 if (LoopStripMiningIter == 0) {
698 // Check for SafePoint on backedge and remove
699 Node *sfpt = x->in(LoopNode::LoopBackControl);
700 if (sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) {
701 lazy_replace( sfpt, iftrue );
702 if (loop->_safepts != NULL) {
703 loop->_safepts->yank(sfpt);
704 }
705 loop->_tail = iftrue;
706 }
707 }
708
709 // Build a canonical trip test.
710 // Clone code, as old values may be in use.
711 incr = incr->clone();
712 incr->set_req(1,phi);
713 incr->set_req(2,stride);
714 incr = _igvn.register_new_node_with_optimizer(incr);
715 set_early_ctrl( incr );
716 _igvn.rehash_node_delayed(phi);
717 phi->set_req_X( LoopNode::LoopBackControl, incr, &_igvn );
718
719 // If phi type is more restrictive than Int, raise to
720 // Int to prevent (almost) infinite recursion in igvn
721 // which can only handle integer types for constants or minint..maxint.
722 if (!TypeInt::INT->higher_equal(phi->bottom_type())) {
723 Node* nphi = PhiNode::make(phi->in(0), phi->in(LoopNode::EntryControl), TypeInt::INT);
724 nphi->set_req(LoopNode::LoopBackControl, phi->in(LoopNode::LoopBackControl));
725 nphi = _igvn.register_new_node_with_optimizer(nphi);
726 set_ctrl(nphi, get_ctrl(phi));
727 _igvn.replace_node(phi, nphi);
728 phi = nphi->as_Phi();
729 }
730 cmp = cmp->clone();
731 cmp->set_req(1,incr);
732 cmp->set_req(2,limit);
733 cmp = _igvn.register_new_node_with_optimizer(cmp);
734 set_ctrl(cmp, iff->in(0));
735
736 test = test->clone()->as_Bool();
737 (*(BoolTest*)&test->_test)._test = bt;
738 test->set_req(1,cmp);
739 _igvn.register_new_node_with_optimizer(test);
740 set_ctrl(test, iff->in(0));
741
742 // Replace the old IfNode with a new LoopEndNode
743 Node *lex = _igvn.register_new_node_with_optimizer(new CountedLoopEndNode( iff->in(0), test, cl_prob, iff->as_If()->_fcnt ));
744 IfNode *le = lex->as_If();
745 uint dd = dom_depth(iff);
746 set_idom(le, le->in(0), dd); // Update dominance for loop exit
747 set_loop(le, loop);
748
749 // Get the loop-exit control
750 Node *iffalse = iff->as_If()->proj_out(!(iftrue_op == Op_IfTrue));
751
752 // Need to swap loop-exit and loop-back control?
753 if (iftrue_op == Op_IfFalse) {
754 Node *ift2=_igvn.register_new_node_with_optimizer(new IfTrueNode (le));
755 Node *iff2=_igvn.register_new_node_with_optimizer(new IfFalseNode(le));
756
757 loop->_tail = back_control = ift2;
758 set_loop(ift2, loop);
759 set_loop(iff2, get_loop(iffalse));
760
761 // Lazy update of 'get_ctrl' mechanism.
762 lazy_replace(iffalse, iff2);
763 lazy_replace(iftrue, ift2);
764
765 // Swap names
766 iffalse = iff2;
767 iftrue = ift2;
768 } else {
769 _igvn.rehash_node_delayed(iffalse);
770 _igvn.rehash_node_delayed(iftrue);
771 iffalse->set_req_X( 0, le, &_igvn );
772 iftrue ->set_req_X( 0, le, &_igvn );
773 }
774
775 set_idom(iftrue, le, dd+1);
776 set_idom(iffalse, le, dd+1);
777 assert(iff->outcnt() == 0, "should be dead now");
778 lazy_replace( iff, le ); // fix 'get_ctrl'
779
780 Node *sfpt2 = le->in(0);
781
782 Node* entry_control = init_control;
783 bool strip_mine_loop = LoopStripMiningIter > 1 && loop->_child == NULL &&
784 sfpt2->Opcode() == Op_SafePoint && !loop->_has_call;
785 IdealLoopTree* outer_ilt = NULL;
786 if (strip_mine_loop) {
787 outer_ilt = create_outer_strip_mined_loop(test, cmp, init_control, loop,
788 cl_prob, le->_fcnt, entry_control,
789 iffalse);
790 }
791
792 // Now setup a new CountedLoopNode to replace the existing LoopNode
793 CountedLoopNode *l = new CountedLoopNode(entry_control, back_control);
794 l->set_unswitch_count(x->as_Loop()->unswitch_count()); // Preserve
795 // The following assert is approximately true, and defines the intention
796 // of can_be_counted_loop. It fails, however, because phase->type
797 // is not yet initialized for this loop and its parts.
798 //assert(l->can_be_counted_loop(this), "sanity");
799 _igvn.register_new_node_with_optimizer(l);
800 set_loop(l, loop);
801 loop->_head = l;
802 // Fix all data nodes placed at the old loop head.
803 // Uses the lazy-update mechanism of 'get_ctrl'.
804 lazy_replace( x, l );
805 set_idom(l, entry_control, dom_depth(entry_control) + 1);
806
807 if (LoopStripMiningIter == 0 || strip_mine_loop) {
808 // Check for immediately preceding SafePoint and remove
809 if (sfpt2->Opcode() == Op_SafePoint && (LoopStripMiningIter != 0 || is_deleteable_safept(sfpt2))) {
810 if (strip_mine_loop) {
811 Node* outer_le = outer_ilt->_tail->in(0);
812 Node* sfpt = sfpt2->clone();
813 sfpt->set_req(0, iffalse);
814 outer_le->set_req(0, sfpt);
815 register_control(sfpt, outer_ilt, iffalse);
816 set_idom(outer_le, sfpt, dom_depth(sfpt));
817 }
818 lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control));
819 if (loop->_safepts != NULL) {
820 loop->_safepts->yank(sfpt2);
821 }
822 }
823 }
824
825 // Free up intermediate goo
826 _igvn.remove_dead_node(hook);
827
828 #ifdef ASSERT
829 assert(l->is_valid_counted_loop(), "counted loop shape is messed up");
830 assert(l == loop->_head && l->phi() == phi && l->loopexit_or_null() == lex, "" );
831 #endif
832 #ifndef PRODUCT
833 if (TraceLoopOpts) {
834 tty->print("Counted ");
835 loop->dump_head();
836 }
837 #endif
838
839 C->print_method(PHASE_AFTER_CLOOPS, 3);
840
841 // Capture bounds of the loop in the induction variable Phi before
842 // subsequent transformation (iteration splitting) obscures the
843 // bounds
844 l->phi()->as_Phi()->set_type(l->phi()->Value(&_igvn));
845
846 if (strip_mine_loop) {
847 l->mark_strip_mined();
848 l->verify_strip_mined(1);
849 outer_ilt->_head->as_Loop()->verify_strip_mined(1);
850 loop = outer_ilt;
851 }
852
853 return true;
854 }
855
856 //----------------------exact_limit-------------------------------------------
857 Node* PhaseIdealLoop::exact_limit( IdealLoopTree *loop ) {
858 assert(loop->_head->is_CountedLoop(), "");
859 CountedLoopNode *cl = loop->_head->as_CountedLoop();
860 assert(cl->is_valid_counted_loop(), "");
861
862 if (ABS(cl->stride_con()) == 1 ||
863 cl->limit()->Opcode() == Op_LoopLimit) {
864 // Old code has exact limit (it could be incorrect in case of int overflow).
865 // Loop limit is exact with stride == 1. And loop may already have exact limit.
866 return cl->limit();
867 }
868 Node *limit = NULL;
869 #ifdef ASSERT
870 BoolTest::mask bt = cl->loopexit()->test_trip();
871 assert(bt == BoolTest::lt || bt == BoolTest::gt, "canonical test is expected");
872 #endif
873 if (cl->has_exact_trip_count()) {
874 // Simple case: loop has constant boundaries.
875 // Use jlongs to avoid integer overflow.
876 int stride_con = cl->stride_con();
877 jlong init_con = cl->init_trip()->get_int();
878 jlong limit_con = cl->limit()->get_int();
879 julong trip_cnt = cl->trip_count();
880 jlong final_con = init_con + trip_cnt*stride_con;
881 int final_int = (int)final_con;
882 // The final value should be in integer range since the loop
883 // is counted and the limit was checked for overflow.
884 assert(final_con == (jlong)final_int, "final value should be integer");
885 limit = _igvn.intcon(final_int);
886 } else {
887 // Create new LoopLimit node to get exact limit (final iv value).
888 limit = new LoopLimitNode(C, cl->init_trip(), cl->limit(), cl->stride());
889 register_new_node(limit, cl->in(LoopNode::EntryControl));
890 }
891 assert(limit != NULL, "sanity");
892 return limit;
893 }
894
895 //------------------------------Ideal------------------------------------------
896 // Return a node which is more "ideal" than the current node.
897 // Attempt to convert into a counted-loop.
898 Node *LoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
899 if (!can_be_counted_loop(phase) && !is_OuterStripMinedLoop()) {
900 phase->C->set_major_progress();
901 }
902 return RegionNode::Ideal(phase, can_reshape);
903 }
904
905 void LoopNode::verify_strip_mined(int expect_skeleton) const {
906 #ifdef ASSERT
907 const OuterStripMinedLoopNode* outer = NULL;
908 const CountedLoopNode* inner = NULL;
909 if (is_strip_mined()) {
910 assert(is_CountedLoop(), "no Loop should be marked strip mined");
911 inner = as_CountedLoop();
912 outer = inner->in(LoopNode::EntryControl)->as_OuterStripMinedLoop();
913 } else if (is_OuterStripMinedLoop()) {
914 outer = this->as_OuterStripMinedLoop();
915 inner = outer->unique_ctrl_out()->as_CountedLoop();
916 assert(!is_strip_mined(), "outer loop shouldn't be marked strip mined");
917 }
918 if (inner != NULL || outer != NULL) {
919 assert(inner != NULL && outer != NULL, "missing loop in strip mined nest");
920 Node* outer_tail = outer->in(LoopNode::LoopBackControl);
921 Node* outer_le = outer_tail->in(0);
922 assert(outer_le->Opcode() == Op_OuterStripMinedLoopEnd, "tail of outer loop should be an If");
923 Node* sfpt = outer_le->in(0);
924 assert(sfpt->Opcode() == Op_SafePoint, "where's the safepoint?");
925 Node* inner_out = sfpt->in(0);
926 if (inner_out->outcnt() != 1) {
927 ResourceMark rm;
928 Unique_Node_List wq;
929
930 for (DUIterator_Fast imax, i = inner_out->fast_outs(imax); i < imax; i++) {
931 Node* u = inner_out->fast_out(i);
932 if (u == sfpt) {
933 continue;
934 }
935 wq.clear();
936 wq.push(u);
937 bool found_sfpt = false;
938 for (uint next = 0; next < wq.size() && !found_sfpt; next++) {
939 Node *n = wq.at(next);
940 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && !found_sfpt; i++) {
941 Node* u = n->fast_out(i);
942 if (u == sfpt) {
943 found_sfpt = true;
944 }
945 if (!u->is_CFG()) {
946 wq.push(u);
947 }
948 }
949 }
950 assert(found_sfpt, "no node in loop that's not input to safepoint");
951 }
952 }
953 CountedLoopEndNode* cle = inner_out->in(0)->as_CountedLoopEnd();
954 assert(cle == inner->loopexit_or_null(), "mismatch");
955 bool has_skeleton = outer_le->in(1)->bottom_type()->singleton() && outer_le->in(1)->bottom_type()->is_int()->get_con() == 0;
956 if (has_skeleton) {
957 assert(expect_skeleton == 1 || expect_skeleton == -1, "unexpected skeleton node");
958 assert(outer->outcnt() == 2, "only phis");
959 } else {
960 assert(expect_skeleton == 0 || expect_skeleton == -1, "no skeleton node?");
961 uint phis = 0;
962 for (DUIterator_Fast imax, i = inner->fast_outs(imax); i < imax; i++) {
963 Node* u = inner->fast_out(i);
964 if (u->is_Phi()) {
965 phis++;
966 }
967 }
968 for (DUIterator_Fast imax, i = outer->fast_outs(imax); i < imax; i++) {
969 Node* u = outer->fast_out(i);
970 assert(u == outer || u == inner || u->is_Phi(), "nothing between inner and outer loop");
971 }
972 uint stores = 0;
973 for (DUIterator_Fast imax, i = inner_out->fast_outs(imax); i < imax; i++) {
974 Node* u = inner_out->fast_out(i);
975 if (u->is_Store()) {
976 stores++;
977 }
978 }
979 assert(outer->outcnt() >= phis + 2 && outer->outcnt() <= phis + 2 + stores + 1, "only phis");
980 }
981 assert(sfpt->outcnt() == 1, "no data node");
982 assert(outer_tail->outcnt() == 1 || !has_skeleton, "no data node");
983 }
984 #endif
985 }
986
987 //=============================================================================
988 //------------------------------Ideal------------------------------------------
989 // Return a node which is more "ideal" than the current node.
990 // Attempt to convert into a counted-loop.
991 Node *CountedLoopNode::Ideal(PhaseGVN *phase, bool can_reshape) {
992 return RegionNode::Ideal(phase, can_reshape);
993 }
994
995 //------------------------------dump_spec--------------------------------------
996 // Dump special per-node info
997 #ifndef PRODUCT
998 void CountedLoopNode::dump_spec(outputStream *st) const {
999 LoopNode::dump_spec(st);
1000 if (stride_is_con()) {
1001 st->print("stride: %d ",stride_con());
1002 }
1003 if (is_pre_loop ()) st->print("pre of N%d" , _main_idx);
1004 if (is_main_loop()) st->print("main of N%d", _idx);
1005 if (is_post_loop()) st->print("post of N%d", _main_idx);
1006 if (is_strip_mined()) st->print(" strip mined");
1007 }
1008 #endif
1009
1010 //=============================================================================
1011 int CountedLoopEndNode::stride_con() const {
1012 return stride()->bottom_type()->is_int()->get_con();
1013 }
1014
1015 //=============================================================================
1016 //------------------------------Value-----------------------------------------
1017 const Type* LoopLimitNode::Value(PhaseGVN* phase) const {
1018 const Type* init_t = phase->type(in(Init));
1019 const Type* limit_t = phase->type(in(Limit));
1020 const Type* stride_t = phase->type(in(Stride));
1021 // Either input is TOP ==> the result is TOP
1022 if (init_t == Type::TOP) return Type::TOP;
1023 if (limit_t == Type::TOP) return Type::TOP;
1024 if (stride_t == Type::TOP) return Type::TOP;
1025
1026 int stride_con = stride_t->is_int()->get_con();
1027 if (stride_con == 1)
1028 return NULL; // Identity
1029
1030 if (init_t->is_int()->is_con() && limit_t->is_int()->is_con()) {
1031 // Use jlongs to avoid integer overflow.
1032 jlong init_con = init_t->is_int()->get_con();
1033 jlong limit_con = limit_t->is_int()->get_con();
1034 int stride_m = stride_con - (stride_con > 0 ? 1 : -1);
1035 jlong trip_count = (limit_con - init_con + stride_m)/stride_con;
1036 jlong final_con = init_con + stride_con*trip_count;
1037 int final_int = (int)final_con;
1038 // The final value should be in integer range since the loop
1039 // is counted and the limit was checked for overflow.
1040 assert(final_con == (jlong)final_int, "final value should be integer");
1041 return TypeInt::make(final_int);
1042 }
1043
1044 return bottom_type(); // TypeInt::INT
1045 }
1046
1047 //------------------------------Ideal------------------------------------------
1048 // Return a node which is more "ideal" than the current node.
1049 Node *LoopLimitNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1050 if (phase->type(in(Init)) == Type::TOP ||
1051 phase->type(in(Limit)) == Type::TOP ||
1052 phase->type(in(Stride)) == Type::TOP)
1053 return NULL; // Dead
1054
1055 int stride_con = phase->type(in(Stride))->is_int()->get_con();
1056 if (stride_con == 1)
1057 return NULL; // Identity
1058
1059 if (in(Init)->is_Con() && in(Limit)->is_Con())
1060 return NULL; // Value
1061
1062 // Delay following optimizations until all loop optimizations
1063 // done to keep Ideal graph simple.
1064 if (!can_reshape || phase->C->major_progress())
1065 return NULL;
1066
1067 const TypeInt* init_t = phase->type(in(Init) )->is_int();
1068 const TypeInt* limit_t = phase->type(in(Limit))->is_int();
1069 int stride_p;
1070 jlong lim, ini;
1071 julong max;
1072 if (stride_con > 0) {
1073 stride_p = stride_con;
1074 lim = limit_t->_hi;
1075 ini = init_t->_lo;
1076 max = (julong)max_jint;
1077 } else {
1078 stride_p = -stride_con;
1079 lim = init_t->_hi;
1080 ini = limit_t->_lo;
1081 max = (julong)min_jint;
1082 }
1083 julong range = lim - ini + stride_p;
1084 if (range <= max) {
1085 // Convert to integer expression if it is not overflow.
1086 Node* stride_m = phase->intcon(stride_con - (stride_con > 0 ? 1 : -1));
1087 Node *range = phase->transform(new SubINode(in(Limit), in(Init)));
1088 Node *bias = phase->transform(new AddINode(range, stride_m));
1089 Node *trip = phase->transform(new DivINode(0, bias, in(Stride)));
1090 Node *span = phase->transform(new MulINode(trip, in(Stride)));
1091 return new AddINode(span, in(Init)); // exact limit
1092 }
1093
1094 if (is_power_of_2(stride_p) || // divisor is 2^n
1095 !Matcher::has_match_rule(Op_LoopLimit)) { // or no specialized Mach node?
1096 // Convert to long expression to avoid integer overflow
1097 // and let igvn optimizer convert this division.
1098 //
1099 Node* init = phase->transform( new ConvI2LNode(in(Init)));
1100 Node* limit = phase->transform( new ConvI2LNode(in(Limit)));
1101 Node* stride = phase->longcon(stride_con);
1102 Node* stride_m = phase->longcon(stride_con - (stride_con > 0 ? 1 : -1));
1103
1104 Node *range = phase->transform(new SubLNode(limit, init));
1105 Node *bias = phase->transform(new AddLNode(range, stride_m));
1106 Node *span;
1107 if (stride_con > 0 && is_power_of_2(stride_p)) {
1108 // bias >= 0 if stride >0, so if stride is 2^n we can use &(-stride)
1109 // and avoid generating rounding for division. Zero trip guard should
1110 // guarantee that init < limit but sometimes the guard is missing and
1111 // we can get situation when init > limit. Note, for the empty loop
1112 // optimization zero trip guard is generated explicitly which leaves
1113 // only RCE predicate where exact limit is used and the predicate
1114 // will simply fail forcing recompilation.
1115 Node* neg_stride = phase->longcon(-stride_con);
1116 span = phase->transform(new AndLNode(bias, neg_stride));
1117 } else {
1118 Node *trip = phase->transform(new DivLNode(0, bias, stride));
1119 span = phase->transform(new MulLNode(trip, stride));
1120 }
1121 // Convert back to int
1122 Node *span_int = phase->transform(new ConvL2INode(span));
1123 return new AddINode(span_int, in(Init)); // exact limit
1124 }
1125
1126 return NULL; // No progress
1127 }
1128
1129 //------------------------------Identity---------------------------------------
1130 // If stride == 1 return limit node.
1131 Node* LoopLimitNode::Identity(PhaseGVN* phase) {
1132 int stride_con = phase->type(in(Stride))->is_int()->get_con();
1133 if (stride_con == 1 || stride_con == -1)
1134 return in(Limit);
1135 return this;
1136 }
1137
1138 //=============================================================================
1139 //----------------------match_incr_with_optional_truncation--------------------
1140 // Match increment with optional truncation:
1141 // CHAR: (i+1)&0x7fff, BYTE: ((i+1)<<8)>>8, or SHORT: ((i+1)<<16)>>16
1142 // Return NULL for failure. Success returns the increment node.
1143 Node* CountedLoopNode::match_incr_with_optional_truncation(
1144 Node* expr, Node** trunc1, Node** trunc2, const TypeInt** trunc_type) {
1145 // Quick cutouts:
1146 if (expr == NULL || expr->req() != 3) return NULL;
1147
1148 Node *t1 = NULL;
1149 Node *t2 = NULL;
1150 const TypeInt* trunc_t = TypeInt::INT;
1151 Node* n1 = expr;
1152 int n1op = n1->Opcode();
1153
1154 // Try to strip (n1 & M) or (n1 << N >> N) from n1.
1155 if (n1op == Op_AndI &&
1156 n1->in(2)->is_Con() &&
1157 n1->in(2)->bottom_type()->is_int()->get_con() == 0x7fff) {
1158 // %%% This check should match any mask of 2**K-1.
1159 t1 = n1;
1160 n1 = t1->in(1);
1161 n1op = n1->Opcode();
1162 trunc_t = TypeInt::CHAR;
1163 } else if (n1op == Op_RShiftI &&
1164 n1->in(1) != NULL &&
1165 n1->in(1)->Opcode() == Op_LShiftI &&
1166 n1->in(2) == n1->in(1)->in(2) &&
1167 n1->in(2)->is_Con()) {
1168 jint shift = n1->in(2)->bottom_type()->is_int()->get_con();
1169 // %%% This check should match any shift in [1..31].
1170 if (shift == 16 || shift == 8) {
1171 t1 = n1;
1172 t2 = t1->in(1);
1173 n1 = t2->in(1);
1174 n1op = n1->Opcode();
1175 if (shift == 16) {
1176 trunc_t = TypeInt::SHORT;
1177 } else if (shift == 8) {
1178 trunc_t = TypeInt::BYTE;
1179 }
1180 }
1181 }
1182
1183 // If (maybe after stripping) it is an AddI, we won:
1184 if (n1op == Op_AddI) {
1185 *trunc1 = t1;
1186 *trunc2 = t2;
1187 *trunc_type = trunc_t;
1188 return n1;
1189 }
1190
1191 // failed
1192 return NULL;
1193 }
1194
1195 LoopNode* CountedLoopNode::skip_strip_mined(int expect_skeleton) {
1196 if (is_strip_mined()) {
1197 verify_strip_mined(expect_skeleton);
1198 return in(EntryControl)->as_Loop();
1199 }
1200 return this;
1201 }
1202
1203 OuterStripMinedLoopNode* CountedLoopNode::outer_loop() const {
1204 assert(is_strip_mined(), "not a strip mined loop");
1205 Node* c = in(EntryControl);
1206 if (c == NULL || c->is_top() || !c->is_OuterStripMinedLoop()) {
1207 return NULL;
1208 }
1209 return c->as_OuterStripMinedLoop();
1210 }
1211
1212 IfTrueNode* OuterStripMinedLoopNode::outer_loop_tail() const {
1213 Node* c = in(LoopBackControl);
1214 if (c == NULL || c->is_top()) {
1215 return NULL;
1216 }
1217 return c->as_IfTrue();
1218 }
1219
1220 IfTrueNode* CountedLoopNode::outer_loop_tail() const {
1221 LoopNode* l = outer_loop();
1222 if (l == NULL) {
1223 return NULL;
1224 }
1225 return l->outer_loop_tail();
1226 }
1227
1228 OuterStripMinedLoopEndNode* OuterStripMinedLoopNode::outer_loop_end() const {
1229 IfTrueNode* proj = outer_loop_tail();
1230 if (proj == NULL) {
1231 return NULL;
1232 }
1233 Node* c = proj->in(0);
1234 if (c == NULL || c->is_top() || c->outcnt() != 2) {
1235 return NULL;
1236 }
1237 return c->as_OuterStripMinedLoopEnd();
1238 }
1239
1240 OuterStripMinedLoopEndNode* CountedLoopNode::outer_loop_end() const {
1241 LoopNode* l = outer_loop();
1242 if (l == NULL) {
1243 return NULL;
1244 }
1245 return l->outer_loop_end();
1246 }
1247
1248 IfFalseNode* OuterStripMinedLoopNode::outer_loop_exit() const {
1249 IfNode* le = outer_loop_end();
1250 if (le == NULL) {
1251 return NULL;
1252 }
1253 Node* c = le->proj_out_or_null(false);
1254 if (c == NULL) {
1255 return NULL;
1256 }
1257 return c->as_IfFalse();
1258 }
1259
1260 IfFalseNode* CountedLoopNode::outer_loop_exit() const {
1261 LoopNode* l = outer_loop();
1262 if (l == NULL) {
1263 return NULL;
1264 }
1265 return l->outer_loop_exit();
1266 }
1267
1268 SafePointNode* OuterStripMinedLoopNode::outer_safepoint() const {
1269 IfNode* le = outer_loop_end();
1270 if (le == NULL) {
1271 return NULL;
1272 }
1273 Node* c = le->in(0);
1274 if (c == NULL || c->is_top()) {
1275 return NULL;
1276 }
1277 assert(c->Opcode() == Op_SafePoint, "broken outer loop");
1278 return c->as_SafePoint();
1279 }
1280
1281 SafePointNode* CountedLoopNode::outer_safepoint() const {
1282 LoopNode* l = outer_loop();
1283 if (l == NULL) {
1284 return NULL;
1285 }
1286 return l->outer_safepoint();
1287 }
1288
1289 Node* CountedLoopNode::skip_predicates_from_entry(Node* ctrl) {
1290 while (ctrl != NULL && ctrl->is_Proj() && ctrl->in(0)->is_If() &&
1291 ctrl->in(0)->as_If()->proj_out(1-ctrl->as_Proj()->_con)->outcnt() == 1 &&
1292 ctrl->in(0)->as_If()->proj_out(1-ctrl->as_Proj()->_con)->unique_out()->Opcode() == Op_Halt) {
1293 ctrl = ctrl->in(0)->in(0);
1294 }
1295
1296 return ctrl;
1297 }
1298
1299 Node* CountedLoopNode::skip_predicates() {
1300 if (is_main_loop()) {
1301 Node* ctrl = skip_strip_mined()->in(LoopNode::EntryControl);
1302
1303 return skip_predicates_from_entry(ctrl);
1304 }
1305 return in(LoopNode::EntryControl);
1306 }
1307
1308 void OuterStripMinedLoopNode::adjust_strip_mined_loop(PhaseIterGVN* igvn) {
1309 // Look for the outer & inner strip mined loop, reduce number of
1310 // iterations of the inner loop, set exit condition of outer loop,
1311 // construct required phi nodes for outer loop.
1312 CountedLoopNode* inner_cl = unique_ctrl_out()->as_CountedLoop();
1313 assert(inner_cl->is_strip_mined(), "inner loop should be strip mined");
1314 Node* inner_iv_phi = inner_cl->phi();
1315 if (inner_iv_phi == NULL) {
1316 IfNode* outer_le = outer_loop_end();
1317 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
1318 igvn->replace_node(outer_le, iff);
1319 inner_cl->clear_strip_mined();
1320 return;
1321 }
1322 CountedLoopEndNode* inner_cle = inner_cl->loopexit();
1323
1324 int stride = inner_cl->stride_con();
1325 jlong scaled_iters_long = ((jlong)LoopStripMiningIter) * ABS(stride);
1326 int scaled_iters = (int)scaled_iters_long;
1327 int short_scaled_iters = LoopStripMiningIterShortLoop* ABS(stride);
1328 const TypeInt* inner_iv_t = igvn->type(inner_iv_phi)->is_int();
1329 jlong iter_estimate = (jlong)inner_iv_t->_hi - (jlong)inner_iv_t->_lo;
1330 assert(iter_estimate > 0, "broken");
1331 if ((jlong)scaled_iters != scaled_iters_long || iter_estimate <= short_scaled_iters) {
1332 // Remove outer loop and safepoint (too few iterations)
1333 Node* outer_sfpt = outer_safepoint();
1334 Node* outer_out = outer_loop_exit();
1335 igvn->replace_node(outer_out, outer_sfpt->in(0));
1336 igvn->replace_input_of(outer_sfpt, 0, igvn->C->top());
1337 inner_cl->clear_strip_mined();
1338 return;
1339 }
1340 if (iter_estimate <= scaled_iters_long) {
1341 // We would only go through one iteration of
1342 // the outer loop: drop the outer loop but
1343 // keep the safepoint so we don't run for
1344 // too long without a safepoint
1345 IfNode* outer_le = outer_loop_end();
1346 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
1347 igvn->replace_node(outer_le, iff);
1348 inner_cl->clear_strip_mined();
1349 return;
1350 }
1351
1352 Node* cle_tail = inner_cle->proj_out(true);
1353 ResourceMark rm;
1354 Node_List old_new;
1355 if (cle_tail->outcnt() > 1) {
1356 // Look for nodes on backedge of inner loop and clone them
1357 Unique_Node_List backedge_nodes;
1358 for (DUIterator_Fast imax, i = cle_tail->fast_outs(imax); i < imax; i++) {
1359 Node* u = cle_tail->fast_out(i);
1360 if (u != inner_cl) {
1361 assert(!u->is_CFG(), "control flow on the backedge?");
1362 backedge_nodes.push(u);
1363 }
1364 }
1365 uint last = igvn->C->unique();
1366 for (uint next = 0; next < backedge_nodes.size(); next++) {
1367 Node* n = backedge_nodes.at(next);
1368 old_new.map(n->_idx, n->clone());
1369 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
1370 Node* u = n->fast_out(i);
1371 assert(!u->is_CFG(), "broken");
1372 if (u->_idx >= last) {
1373 continue;
1374 }
1375 if (!u->is_Phi()) {
1376 backedge_nodes.push(u);
1377 } else {
1378 assert(u->in(0) == inner_cl, "strange phi on the backedge");
1379 }
1380 }
1381 }
1382 // Put the clones on the outer loop backedge
1383 Node* le_tail = outer_loop_tail();
1384 for (uint next = 0; next < backedge_nodes.size(); next++) {
1385 Node *n = old_new[backedge_nodes.at(next)->_idx];
1386 for (uint i = 1; i < n->req(); i++) {
1387 if (n->in(i) != NULL && old_new[n->in(i)->_idx] != NULL) {
1388 n->set_req(i, old_new[n->in(i)->_idx]);
1389 }
1390 }
1391 if (n->in(0) != NULL && n->in(0) == cle_tail) {
1392 n->set_req(0, le_tail);
1393 }
1394 igvn->register_new_node_with_optimizer(n);
1395 }
1396 }
1397
1398 Node* iv_phi = NULL;
1399 // Make a clone of each phi in the inner loop
1400 // for the outer loop
1401 for (uint i = 0; i < inner_cl->outcnt(); i++) {
1402 Node* u = inner_cl->raw_out(i);
1403 if (u->is_Phi()) {
1404 assert(u->in(0) == inner_cl, "inconsistent");
1405 Node* phi = u->clone();
1406 phi->set_req(0, this);
1407 Node* be = old_new[phi->in(LoopNode::LoopBackControl)->_idx];
1408 if (be != NULL) {
1409 phi->set_req(LoopNode::LoopBackControl, be);
1410 }
1411 phi = igvn->transform(phi);
1412 igvn->replace_input_of(u, LoopNode::EntryControl, phi);
1413 if (u == inner_iv_phi) {
1414 iv_phi = phi;
1415 }
1416 }
1417 }
1418 Node* cle_out = inner_cle->proj_out(false);
1419 if (cle_out->outcnt() > 1) {
1420 // Look for chains of stores that were sunk
1421 // out of the inner loop and are in the outer loop
1422 for (DUIterator_Fast imax, i = cle_out->fast_outs(imax); i < imax; i++) {
1423 Node* u = cle_out->fast_out(i);
1424 if (u->is_Store()) {
1425 Node* first = u;
1426 for(;;) {
1427 Node* next = first->in(MemNode::Memory);
1428 if (!next->is_Store() || next->in(0) != cle_out) {
1429 break;
1430 }
1431 first = next;
1432 }
1433 Node* last = u;
1434 for(;;) {
1435 Node* next = NULL;
1436 for (DUIterator_Fast jmax, j = last->fast_outs(jmax); j < jmax; j++) {
1437 Node* uu = last->fast_out(j);
1438 if (uu->is_Store() && uu->in(0) == cle_out) {
1439 assert(next == NULL, "only one in the outer loop");
1440 next = uu;
1441 }
1442 }
1443 if (next == NULL) {
1444 break;
1445 }
1446 last = next;
1447 }
1448 Node* phi = NULL;
1449 for (DUIterator_Fast jmax, j = fast_outs(jmax); j < jmax; j++) {
1450 Node* uu = fast_out(j);
1451 if (uu->is_Phi()) {
1452 Node* be = uu->in(LoopNode::LoopBackControl);
1453 if (be->is_Store() && old_new[be->_idx] != NULL) {
1454 assert(false, "store on the backedge + sunk stores: unsupported");
1455 // drop outer loop
1456 IfNode* outer_le = outer_loop_end();
1457 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
1458 igvn->replace_node(outer_le, iff);
1459 inner_cl->clear_strip_mined();
1460 return;
1461 }
1462 if (be == last || be == first->in(MemNode::Memory)) {
1463 assert(phi == NULL, "only one phi");
1464 phi = uu;
1465 }
1466 }
1467 }
1468 #ifdef ASSERT
1469 for (DUIterator_Fast jmax, j = fast_outs(jmax); j < jmax; j++) {
1470 Node* uu = fast_out(j);
1471 if (uu->is_Phi() && uu->bottom_type() == Type::MEMORY) {
1472 if (uu->adr_type() == igvn->C->get_adr_type(igvn->C->get_alias_index(u->adr_type()))) {
1473 assert(phi == uu, "what's that phi?");
1474 } else if (uu->adr_type() == TypePtr::BOTTOM) {
1475 Node* n = uu->in(LoopNode::LoopBackControl);
1476 uint limit = igvn->C->live_nodes();
1477 uint i = 0;
1478 while (n != uu) {
1479 i++;
1480 assert(i < limit, "infinite loop");
1481 if (n->is_Proj()) {
1482 n = n->in(0);
1483 } else if (n->is_SafePoint() || n->is_MemBar()) {
1484 n = n->in(TypeFunc::Memory);
1485 } else if (n->is_Phi()) {
1486 n = n->in(1);
1487 } else if (n->is_MergeMem()) {
1488 n = n->as_MergeMem()->memory_at(igvn->C->get_alias_index(u->adr_type()));
1489 } else if (n->is_Store() || n->is_LoadStore() || n->is_ClearArray()) {
1490 n = n->in(MemNode::Memory);
1491 } else {
1492 n->dump();
1493 ShouldNotReachHere();
1494 }
1495 }
1496 }
1497 }
1498 }
1499 #endif
1500 if (phi == NULL) {
1501 // If the an entire chains was sunk, the
1502 // inner loop has no phi for that memory
1503 // slice, create one for the outer loop
1504 phi = PhiNode::make(this, first->in(MemNode::Memory), Type::MEMORY,
1505 igvn->C->get_adr_type(igvn->C->get_alias_index(u->adr_type())));
1506 phi->set_req(LoopNode::LoopBackControl, last);
1507 phi = igvn->transform(phi);
1508 igvn->replace_input_of(first, MemNode::Memory, phi);
1509 } else {
1510 // Or fix the outer loop fix to include
1511 // that chain of stores.
1512 Node* be = phi->in(LoopNode::LoopBackControl);
1513 assert(!(be->is_Store() && old_new[be->_idx] != NULL), "store on the backedge + sunk stores: unsupported");
1514 if (be == first->in(MemNode::Memory)) {
1515 if (be == phi->in(LoopNode::LoopBackControl)) {
1516 igvn->replace_input_of(phi, LoopNode::LoopBackControl, last);
1517 } else {
1518 igvn->replace_input_of(be, MemNode::Memory, last);
1519 }
1520 } else {
1521 #ifdef ASSERT
1522 if (be == phi->in(LoopNode::LoopBackControl)) {
1523 assert(phi->in(LoopNode::LoopBackControl) == last, "");
1524 } else {
1525 assert(be->in(MemNode::Memory) == last, "");
1526 }
1527 #endif
1528 }
1529 }
1530 }
1531 }
1532 }
1533
1534 if (iv_phi != NULL) {
1535 // Now adjust the inner loop's exit condition
1536 Node* limit = inner_cl->limit();
1537 Node* sub = NULL;
1538 if (stride > 0) {
1539 sub = igvn->transform(new SubINode(limit, iv_phi));
1540 } else {
1541 sub = igvn->transform(new SubINode(iv_phi, limit));
1542 }
1543 Node* min = igvn->transform(new MinINode(sub, igvn->intcon(scaled_iters)));
1544 Node* new_limit = NULL;
1545 if (stride > 0) {
1546 new_limit = igvn->transform(new AddINode(min, iv_phi));
1547 } else {
1548 new_limit = igvn->transform(new SubINode(iv_phi, min));
1549 }
1550 Node* cmp = inner_cle->cmp_node()->clone();
1551 igvn->replace_input_of(cmp, 2, new_limit);
1552 Node* bol = inner_cle->in(CountedLoopEndNode::TestValue)->clone();
1553 cmp->set_req(2, limit);
1554 bol->set_req(1, igvn->transform(cmp));
1555 igvn->replace_input_of(outer_loop_end(), 1, igvn->transform(bol));
1556 } else {
1557 assert(false, "should be able to adjust outer loop");
1558 IfNode* outer_le = outer_loop_end();
1559 Node* iff = igvn->transform(new IfNode(outer_le->in(0), outer_le->in(1), outer_le->_prob, outer_le->_fcnt));
1560 igvn->replace_node(outer_le, iff);
1561 inner_cl->clear_strip_mined();
1562 }
1563 }
1564
1565 const Type* OuterStripMinedLoopEndNode::Value(PhaseGVN* phase) const {
1566 if (!in(0)) return Type::TOP;
1567 if (phase->type(in(0)) == Type::TOP)
1568 return Type::TOP;
1569
1570 return TypeTuple::IFBOTH;
1571 }
1572
1573 Node *OuterStripMinedLoopEndNode::Ideal(PhaseGVN *phase, bool can_reshape) {
1574 if (remove_dead_region(phase, can_reshape)) return this;
1575
1576 return NULL;
1577 }
1578
1579 //------------------------------filtered_type--------------------------------
1580 // Return a type based on condition control flow
1581 // A successful return will be a type that is restricted due
1582 // to a series of dominating if-tests, such as:
1583 // if (i < 10) {
1584 // if (i > 0) {
1585 // here: "i" type is [1..10)
1586 // }
1587 // }
1588 // or a control flow merge
1589 // if (i < 10) {
1590 // do {
1591 // phi( , ) -- at top of loop type is [min_int..10)
1592 // i = ?
1593 // } while ( i < 10)
1594 //
1595 const TypeInt* PhaseIdealLoop::filtered_type( Node *n, Node* n_ctrl) {
1596 assert(n && n->bottom_type()->is_int(), "must be int");
1597 const TypeInt* filtered_t = NULL;
1598 if (!n->is_Phi()) {
1599 assert(n_ctrl != NULL || n_ctrl == C->top(), "valid control");
1600 filtered_t = filtered_type_from_dominators(n, n_ctrl);
1601
1602 } else {
1603 Node* phi = n->as_Phi();
1604 Node* region = phi->in(0);
1605 assert(n_ctrl == NULL || n_ctrl == region, "ctrl parameter must be region");
1606 if (region && region != C->top()) {
1607 for (uint i = 1; i < phi->req(); i++) {
1608 Node* val = phi->in(i);
1609 Node* use_c = region->in(i);
1610 const TypeInt* val_t = filtered_type_from_dominators(val, use_c);
1611 if (val_t != NULL) {
1612 if (filtered_t == NULL) {
1613 filtered_t = val_t;
1614 } else {
1615 filtered_t = filtered_t->meet(val_t)->is_int();
1616 }
1617 }
1618 }
1619 }
1620 }
1621 const TypeInt* n_t = _igvn.type(n)->is_int();
1622 if (filtered_t != NULL) {
1623 n_t = n_t->join(filtered_t)->is_int();
1624 }
1625 return n_t;
1626 }
1627
1628
1629 //------------------------------filtered_type_from_dominators--------------------------------
1630 // Return a possibly more restrictive type for val based on condition control flow of dominators
1631 const TypeInt* PhaseIdealLoop::filtered_type_from_dominators( Node* val, Node *use_ctrl) {
1632 if (val->is_Con()) {
1633 return val->bottom_type()->is_int();
1634 }
1635 uint if_limit = 10; // Max number of dominating if's visited
1636 const TypeInt* rtn_t = NULL;
1637
1638 if (use_ctrl && use_ctrl != C->top()) {
1639 Node* val_ctrl = get_ctrl(val);
1640 uint val_dom_depth = dom_depth(val_ctrl);
1641 Node* pred = use_ctrl;
1642 uint if_cnt = 0;
1643 while (if_cnt < if_limit) {
1644 if ((pred->Opcode() == Op_IfTrue || pred->Opcode() == Op_IfFalse)) {
1645 if_cnt++;
1646 const TypeInt* if_t = IfNode::filtered_int_type(&_igvn, val, pred);
1647 if (if_t != NULL) {
1648 if (rtn_t == NULL) {
1649 rtn_t = if_t;
1650 } else {
1651 rtn_t = rtn_t->join(if_t)->is_int();
1652 }
1653 }
1654 }
1655 pred = idom(pred);
1656 if (pred == NULL || pred == C->top()) {
1657 break;
1658 }
1659 // Stop if going beyond definition block of val
1660 if (dom_depth(pred) < val_dom_depth) {
1661 break;
1662 }
1663 }
1664 }
1665 return rtn_t;
1666 }
1667
1668
1669 //------------------------------dump_spec--------------------------------------
1670 // Dump special per-node info
1671 #ifndef PRODUCT
1672 void CountedLoopEndNode::dump_spec(outputStream *st) const {
1673 if( in(TestValue) != NULL && in(TestValue)->is_Bool() ) {
1674 BoolTest bt( test_trip()); // Added this for g++.
1675
1676 st->print("[");
1677 bt.dump_on(st);
1678 st->print("]");
1679 }
1680 st->print(" ");
1681 IfNode::dump_spec(st);
1682 }
1683 #endif
1684
1685 //=============================================================================
1686 //------------------------------is_member--------------------------------------
1687 // Is 'l' a member of 'this'?
1688 bool IdealLoopTree::is_member(const IdealLoopTree *l) const {
1689 while( l->_nest > _nest ) l = l->_parent;
1690 return l == this;
1691 }
1692
1693 //------------------------------set_nest---------------------------------------
1694 // Set loop tree nesting depth. Accumulate _has_call bits.
1695 int IdealLoopTree::set_nest( uint depth ) {
1696 _nest = depth;
1697 int bits = _has_call;
1698 if( _child ) bits |= _child->set_nest(depth+1);
1699 if( bits ) _has_call = 1;
1700 if( _next ) bits |= _next ->set_nest(depth );
1701 return bits;
1702 }
1703
1704 //------------------------------split_fall_in----------------------------------
1705 // Split out multiple fall-in edges from the loop header. Move them to a
1706 // private RegionNode before the loop. This becomes the loop landing pad.
1707 void IdealLoopTree::split_fall_in( PhaseIdealLoop *phase, int fall_in_cnt ) {
1708 PhaseIterGVN &igvn = phase->_igvn;
1709 uint i;
1710
1711 // Make a new RegionNode to be the landing pad.
1712 Node *landing_pad = new RegionNode( fall_in_cnt+1 );
1713 phase->set_loop(landing_pad,_parent);
1714 // Gather all the fall-in control paths into the landing pad
1715 uint icnt = fall_in_cnt;
1716 uint oreq = _head->req();
1717 for( i = oreq-1; i>0; i-- )
1718 if( !phase->is_member( this, _head->in(i) ) )
1719 landing_pad->set_req(icnt--,_head->in(i));
1720
1721 // Peel off PhiNode edges as well
1722 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1723 Node *oj = _head->fast_out(j);
1724 if( oj->is_Phi() ) {
1725 PhiNode* old_phi = oj->as_Phi();
1726 assert( old_phi->region() == _head, "" );
1727 igvn.hash_delete(old_phi); // Yank from hash before hacking edges
1728 Node *p = PhiNode::make_blank(landing_pad, old_phi);
1729 uint icnt = fall_in_cnt;
1730 for( i = oreq-1; i>0; i-- ) {
1731 if( !phase->is_member( this, _head->in(i) ) ) {
1732 p->init_req(icnt--, old_phi->in(i));
1733 // Go ahead and clean out old edges from old phi
1734 old_phi->del_req(i);
1735 }
1736 }
1737 // Search for CSE's here, because ZKM.jar does a lot of
1738 // loop hackery and we need to be a little incremental
1739 // with the CSE to avoid O(N^2) node blow-up.
1740 Node *p2 = igvn.hash_find_insert(p); // Look for a CSE
1741 if( p2 ) { // Found CSE
1742 p->destruct(); // Recover useless new node
1743 p = p2; // Use old node
1744 } else {
1745 igvn.register_new_node_with_optimizer(p, old_phi);
1746 }
1747 // Make old Phi refer to new Phi.
1748 old_phi->add_req(p);
1749 // Check for the special case of making the old phi useless and
1750 // disappear it. In JavaGrande I have a case where this useless
1751 // Phi is the loop limit and prevents recognizing a CountedLoop
1752 // which in turn prevents removing an empty loop.
1753 Node *id_old_phi = old_phi->Identity( &igvn );
1754 if( id_old_phi != old_phi ) { // Found a simple identity?
1755 // Note that I cannot call 'replace_node' here, because
1756 // that will yank the edge from old_phi to the Region and
1757 // I'm mid-iteration over the Region's uses.
1758 for (DUIterator_Last imin, i = old_phi->last_outs(imin); i >= imin; ) {
1759 Node* use = old_phi->last_out(i);
1760 igvn.rehash_node_delayed(use);
1761 uint uses_found = 0;
1762 for (uint j = 0; j < use->len(); j++) {
1763 if (use->in(j) == old_phi) {
1764 if (j < use->req()) use->set_req (j, id_old_phi);
1765 else use->set_prec(j, id_old_phi);
1766 uses_found++;
1767 }
1768 }
1769 i -= uses_found; // we deleted 1 or more copies of this edge
1770 }
1771 }
1772 igvn._worklist.push(old_phi);
1773 }
1774 }
1775 // Finally clean out the fall-in edges from the RegionNode
1776 for( i = oreq-1; i>0; i-- ) {
1777 if( !phase->is_member( this, _head->in(i) ) ) {
1778 _head->del_req(i);
1779 }
1780 }
1781 igvn.rehash_node_delayed(_head);
1782 // Transform landing pad
1783 igvn.register_new_node_with_optimizer(landing_pad, _head);
1784 // Insert landing pad into the header
1785 _head->add_req(landing_pad);
1786 }
1787
1788 //------------------------------split_outer_loop-------------------------------
1789 // Split out the outermost loop from this shared header.
1790 void IdealLoopTree::split_outer_loop( PhaseIdealLoop *phase ) {
1791 PhaseIterGVN &igvn = phase->_igvn;
1792
1793 // Find index of outermost loop; it should also be my tail.
1794 uint outer_idx = 1;
1795 while( _head->in(outer_idx) != _tail ) outer_idx++;
1796
1797 // Make a LoopNode for the outermost loop.
1798 Node *ctl = _head->in(LoopNode::EntryControl);
1799 Node *outer = new LoopNode( ctl, _head->in(outer_idx) );
1800 outer = igvn.register_new_node_with_optimizer(outer, _head);
1801 phase->set_created_loop_node();
1802
1803 // Outermost loop falls into '_head' loop
1804 _head->set_req(LoopNode::EntryControl, outer);
1805 _head->del_req(outer_idx);
1806 // Split all the Phis up between '_head' loop and 'outer' loop.
1807 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1808 Node *out = _head->fast_out(j);
1809 if( out->is_Phi() ) {
1810 PhiNode *old_phi = out->as_Phi();
1811 assert( old_phi->region() == _head, "" );
1812 Node *phi = PhiNode::make_blank(outer, old_phi);
1813 phi->init_req(LoopNode::EntryControl, old_phi->in(LoopNode::EntryControl));
1814 phi->init_req(LoopNode::LoopBackControl, old_phi->in(outer_idx));
1815 phi = igvn.register_new_node_with_optimizer(phi, old_phi);
1816 // Make old Phi point to new Phi on the fall-in path
1817 igvn.replace_input_of(old_phi, LoopNode::EntryControl, phi);
1818 old_phi->del_req(outer_idx);
1819 }
1820 }
1821
1822 // Use the new loop head instead of the old shared one
1823 _head = outer;
1824 phase->set_loop(_head, this);
1825 }
1826
1827 //------------------------------fix_parent-------------------------------------
1828 static void fix_parent( IdealLoopTree *loop, IdealLoopTree *parent ) {
1829 loop->_parent = parent;
1830 if( loop->_child ) fix_parent( loop->_child, loop );
1831 if( loop->_next ) fix_parent( loop->_next , parent );
1832 }
1833
1834 //------------------------------estimate_path_freq-----------------------------
1835 static float estimate_path_freq( Node *n ) {
1836 // Try to extract some path frequency info
1837 IfNode *iff;
1838 for( int i = 0; i < 50; i++ ) { // Skip through a bunch of uncommon tests
1839 uint nop = n->Opcode();
1840 if( nop == Op_SafePoint ) { // Skip any safepoint
1841 n = n->in(0);
1842 continue;
1843 }
1844 if( nop == Op_CatchProj ) { // Get count from a prior call
1845 // Assume call does not always throw exceptions: means the call-site
1846 // count is also the frequency of the fall-through path.
1847 assert( n->is_CatchProj(), "" );
1848 if( ((CatchProjNode*)n)->_con != CatchProjNode::fall_through_index )
1849 return 0.0f; // Assume call exception path is rare
1850 Node *call = n->in(0)->in(0)->in(0);
1851 assert( call->is_Call(), "expect a call here" );
1852 const JVMState *jvms = ((CallNode*)call)->jvms();
1853 ciMethodData* methodData = jvms->method()->method_data();
1854 if (!methodData->is_mature()) return 0.0f; // No call-site data
1855 ciProfileData* data = methodData->bci_to_data(jvms->bci());
1856 if ((data == NULL) || !data->is_CounterData()) {
1857 // no call profile available, try call's control input
1858 n = n->in(0);
1859 continue;
1860 }
1861 return data->as_CounterData()->count()/FreqCountInvocations;
1862 }
1863 // See if there's a gating IF test
1864 Node *n_c = n->in(0);
1865 if( !n_c->is_If() ) break; // No estimate available
1866 iff = n_c->as_If();
1867 if( iff->_fcnt != COUNT_UNKNOWN ) // Have a valid count?
1868 // Compute how much count comes on this path
1869 return ((nop == Op_IfTrue) ? iff->_prob : 1.0f - iff->_prob) * iff->_fcnt;
1870 // Have no count info. Skip dull uncommon-trap like branches.
1871 if( (nop == Op_IfTrue && iff->_prob < PROB_LIKELY_MAG(5)) ||
1872 (nop == Op_IfFalse && iff->_prob > PROB_UNLIKELY_MAG(5)) )
1873 break;
1874 // Skip through never-taken branch; look for a real loop exit.
1875 n = iff->in(0);
1876 }
1877 return 0.0f; // No estimate available
1878 }
1879
1880 //------------------------------merge_many_backedges---------------------------
1881 // Merge all the backedges from the shared header into a private Region.
1882 // Feed that region as the one backedge to this loop.
1883 void IdealLoopTree::merge_many_backedges( PhaseIdealLoop *phase ) {
1884 uint i;
1885
1886 // Scan for the top 2 hottest backedges
1887 float hotcnt = 0.0f;
1888 float warmcnt = 0.0f;
1889 uint hot_idx = 0;
1890 // Loop starts at 2 because slot 1 is the fall-in path
1891 for( i = 2; i < _head->req(); i++ ) {
1892 float cnt = estimate_path_freq(_head->in(i));
1893 if( cnt > hotcnt ) { // Grab hottest path
1894 warmcnt = hotcnt;
1895 hotcnt = cnt;
1896 hot_idx = i;
1897 } else if( cnt > warmcnt ) { // And 2nd hottest path
1898 warmcnt = cnt;
1899 }
1900 }
1901
1902 // See if the hottest backedge is worthy of being an inner loop
1903 // by being much hotter than the next hottest backedge.
1904 if( hotcnt <= 0.0001 ||
1905 hotcnt < 2.0*warmcnt ) hot_idx = 0;// No hot backedge
1906
1907 // Peel out the backedges into a private merge point; peel
1908 // them all except optionally hot_idx.
1909 PhaseIterGVN &igvn = phase->_igvn;
1910
1911 Node *hot_tail = NULL;
1912 // Make a Region for the merge point
1913 Node *r = new RegionNode(1);
1914 for( i = 2; i < _head->req(); i++ ) {
1915 if( i != hot_idx )
1916 r->add_req( _head->in(i) );
1917 else hot_tail = _head->in(i);
1918 }
1919 igvn.register_new_node_with_optimizer(r, _head);
1920 // Plug region into end of loop _head, followed by hot_tail
1921 while( _head->req() > 3 ) _head->del_req( _head->req()-1 );
1922 igvn.replace_input_of(_head, 2, r);
1923 if( hot_idx ) _head->add_req(hot_tail);
1924
1925 // Split all the Phis up between '_head' loop and the Region 'r'
1926 for (DUIterator_Fast jmax, j = _head->fast_outs(jmax); j < jmax; j++) {
1927 Node *out = _head->fast_out(j);
1928 if( out->is_Phi() ) {
1929 PhiNode* n = out->as_Phi();
1930 igvn.hash_delete(n); // Delete from hash before hacking edges
1931 Node *hot_phi = NULL;
1932 Node *phi = new PhiNode(r, n->type(), n->adr_type());
1933 // Check all inputs for the ones to peel out
1934 uint j = 1;
1935 for( uint i = 2; i < n->req(); i++ ) {
1936 if( i != hot_idx )
1937 phi->set_req( j++, n->in(i) );
1938 else hot_phi = n->in(i);
1939 }
1940 // Register the phi but do not transform until whole place transforms
1941 igvn.register_new_node_with_optimizer(phi, n);
1942 // Add the merge phi to the old Phi
1943 while( n->req() > 3 ) n->del_req( n->req()-1 );
1944 igvn.replace_input_of(n, 2, phi);
1945 if( hot_idx ) n->add_req(hot_phi);
1946 }
1947 }
1948
1949
1950 // Insert a new IdealLoopTree inserted below me. Turn it into a clone
1951 // of self loop tree. Turn self into a loop headed by _head and with
1952 // tail being the new merge point.
1953 IdealLoopTree *ilt = new IdealLoopTree( phase, _head, _tail );
1954 phase->set_loop(_tail,ilt); // Adjust tail
1955 _tail = r; // Self's tail is new merge point
1956 phase->set_loop(r,this);
1957 ilt->_child = _child; // New guy has my children
1958 _child = ilt; // Self has new guy as only child
1959 ilt->_parent = this; // new guy has self for parent
1960 ilt->_nest = _nest; // Same nesting depth (for now)
1961
1962 // Starting with 'ilt', look for child loop trees using the same shared
1963 // header. Flatten these out; they will no longer be loops in the end.
1964 IdealLoopTree **pilt = &_child;
1965 while( ilt ) {
1966 if( ilt->_head == _head ) {
1967 uint i;
1968 for( i = 2; i < _head->req(); i++ )
1969 if( _head->in(i) == ilt->_tail )
1970 break; // Still a loop
1971 if( i == _head->req() ) { // No longer a loop
1972 // Flatten ilt. Hang ilt's "_next" list from the end of
1973 // ilt's '_child' list. Move the ilt's _child up to replace ilt.
1974 IdealLoopTree **cp = &ilt->_child;
1975 while( *cp ) cp = &(*cp)->_next; // Find end of child list
1976 *cp = ilt->_next; // Hang next list at end of child list
1977 *pilt = ilt->_child; // Move child up to replace ilt
1978 ilt->_head = NULL; // Flag as a loop UNIONED into parent
1979 ilt = ilt->_child; // Repeat using new ilt
1980 continue; // do not advance over ilt->_child
1981 }
1982 assert( ilt->_tail == hot_tail, "expected to only find the hot inner loop here" );
1983 phase->set_loop(_head,ilt);
1984 }
1985 pilt = &ilt->_child; // Advance to next
1986 ilt = *pilt;
1987 }
1988
1989 if( _child ) fix_parent( _child, this );
1990 }
1991
1992 //------------------------------beautify_loops---------------------------------
1993 // Split shared headers and insert loop landing pads.
1994 // Insert a LoopNode to replace the RegionNode.
1995 // Return TRUE if loop tree is structurally changed.
1996 bool IdealLoopTree::beautify_loops( PhaseIdealLoop *phase ) {
1997 bool result = false;
1998 // Cache parts in locals for easy
1999 PhaseIterGVN &igvn = phase->_igvn;
2000
2001 igvn.hash_delete(_head); // Yank from hash before hacking edges
2002
2003 // Check for multiple fall-in paths. Peel off a landing pad if need be.
2004 int fall_in_cnt = 0;
2005 for( uint i = 1; i < _head->req(); i++ )
2006 if( !phase->is_member( this, _head->in(i) ) )
2007 fall_in_cnt++;
2008 assert( fall_in_cnt, "at least 1 fall-in path" );
2009 if( fall_in_cnt > 1 ) // Need a loop landing pad to merge fall-ins
2010 split_fall_in( phase, fall_in_cnt );
2011
2012 // Swap inputs to the _head and all Phis to move the fall-in edge to
2013 // the left.
2014 fall_in_cnt = 1;
2015 while( phase->is_member( this, _head->in(fall_in_cnt) ) )
2016 fall_in_cnt++;
2017 if( fall_in_cnt > 1 ) {
2018 // Since I am just swapping inputs I do not need to update def-use info
2019 Node *tmp = _head->in(1);
2020 igvn.rehash_node_delayed(_head);
2021 _head->set_req( 1, _head->in(fall_in_cnt) );
2022 _head->set_req( fall_in_cnt, tmp );
2023 // Swap also all Phis
2024 for (DUIterator_Fast imax, i = _head->fast_outs(imax); i < imax; i++) {
2025 Node* phi = _head->fast_out(i);
2026 if( phi->is_Phi() ) {
2027 igvn.rehash_node_delayed(phi); // Yank from hash before hacking edges
2028 tmp = phi->in(1);
2029 phi->set_req( 1, phi->in(fall_in_cnt) );
2030 phi->set_req( fall_in_cnt, tmp );
2031 }
2032 }
2033 }
2034 assert( !phase->is_member( this, _head->in(1) ), "left edge is fall-in" );
2035 assert( phase->is_member( this, _head->in(2) ), "right edge is loop" );
2036
2037 // If I am a shared header (multiple backedges), peel off the many
2038 // backedges into a private merge point and use the merge point as
2039 // the one true backedge.
2040 if( _head->req() > 3 ) {
2041 // Merge the many backedges into a single backedge but leave
2042 // the hottest backedge as separate edge for the following peel.
2043 merge_many_backedges( phase );
2044 result = true;
2045 }
2046
2047 // If I have one hot backedge, peel off myself loop.
2048 // I better be the outermost loop.
2049 if (_head->req() > 3 && !_irreducible) {
2050 split_outer_loop( phase );
2051 result = true;
2052
2053 } else if (!_head->is_Loop() && !_irreducible) {
2054 // Make a new LoopNode to replace the old loop head
2055 Node *l = new LoopNode( _head->in(1), _head->in(2) );
2056 l = igvn.register_new_node_with_optimizer(l, _head);
2057 phase->set_created_loop_node();
2058 // Go ahead and replace _head
2059 phase->_igvn.replace_node( _head, l );
2060 _head = l;
2061 phase->set_loop(_head, this);
2062 }
2063
2064 // Now recursively beautify nested loops
2065 if( _child ) result |= _child->beautify_loops( phase );
2066 if( _next ) result |= _next ->beautify_loops( phase );
2067 return result;
2068 }
2069
2070 //------------------------------allpaths_check_safepts----------------------------
2071 // Allpaths backwards scan from loop tail, terminating each path at first safepoint
2072 // encountered. Helper for check_safepts.
2073 void IdealLoopTree::allpaths_check_safepts(VectorSet &visited, Node_List &stack) {
2074 assert(stack.size() == 0, "empty stack");
2075 stack.push(_tail);
2076 visited.Clear();
2077 visited.set(_tail->_idx);
2078 while (stack.size() > 0) {
2079 Node* n = stack.pop();
2080 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
2081 // Terminate this path
2082 } else if (n->Opcode() == Op_SafePoint) {
2083 if (_phase->get_loop(n) != this) {
2084 if (_required_safept == NULL) _required_safept = new Node_List();
2085 _required_safept->push(n); // save the one closest to the tail
2086 }
2087 // Terminate this path
2088 } else {
2089 uint start = n->is_Region() ? 1 : 0;
2090 uint end = n->is_Region() && !n->is_Loop() ? n->req() : start + 1;
2091 for (uint i = start; i < end; i++) {
2092 Node* in = n->in(i);
2093 assert(in->is_CFG(), "must be");
2094 if (!visited.test_set(in->_idx) && is_member(_phase->get_loop(in))) {
2095 stack.push(in);
2096 }
2097 }
2098 }
2099 }
2100 }
2101
2102 //------------------------------check_safepts----------------------------
2103 // Given dominators, try to find loops with calls that must always be
2104 // executed (call dominates loop tail). These loops do not need non-call
2105 // safepoints (ncsfpt).
2106 //
2107 // A complication is that a safepoint in a inner loop may be needed
2108 // by an outer loop. In the following, the inner loop sees it has a
2109 // call (block 3) on every path from the head (block 2) to the
2110 // backedge (arc 3->2). So it deletes the ncsfpt (non-call safepoint)
2111 // in block 2, _but_ this leaves the outer loop without a safepoint.
2112 //
2113 // entry 0
2114 // |
2115 // v
2116 // outer 1,2 +->1
2117 // | |
2118 // | v
2119 // | 2<---+ ncsfpt in 2
2120 // |_/|\ |
2121 // | v |
2122 // inner 2,3 / 3 | call in 3
2123 // / | |
2124 // v +--+
2125 // exit 4
2126 //
2127 //
2128 // This method creates a list (_required_safept) of ncsfpt nodes that must
2129 // be protected is created for each loop. When a ncsfpt maybe deleted, it
2130 // is first looked for in the lists for the outer loops of the current loop.
2131 //
2132 // The insights into the problem:
2133 // A) counted loops are okay
2134 // B) innermost loops are okay (only an inner loop can delete
2135 // a ncsfpt needed by an outer loop)
2136 // C) a loop is immune from an inner loop deleting a safepoint
2137 // if the loop has a call on the idom-path
2138 // D) a loop is also immune if it has a ncsfpt (non-call safepoint) on the
2139 // idom-path that is not in a nested loop
2140 // E) otherwise, an ncsfpt on the idom-path that is nested in an inner
2141 // loop needs to be prevented from deletion by an inner loop
2142 //
2143 // There are two analyses:
2144 // 1) The first, and cheaper one, scans the loop body from
2145 // tail to head following the idom (immediate dominator)
2146 // chain, looking for the cases (C,D,E) above.
2147 // Since inner loops are scanned before outer loops, there is summary
2148 // information about inner loops. Inner loops can be skipped over
2149 // when the tail of an inner loop is encountered.
2150 //
2151 // 2) The second, invoked if the first fails to find a call or ncsfpt on
2152 // the idom path (which is rare), scans all predecessor control paths
2153 // from the tail to the head, terminating a path when a call or sfpt
2154 // is encountered, to find the ncsfpt's that are closest to the tail.
2155 //
2156 void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) {
2157 // Bottom up traversal
2158 IdealLoopTree* ch = _child;
2159 if (_child) _child->check_safepts(visited, stack);
2160 if (_next) _next ->check_safepts(visited, stack);
2161
2162 if (!_head->is_CountedLoop() && !_has_sfpt && _parent != NULL && !_irreducible) {
2163 bool has_call = false; // call on dom-path
2164 bool has_local_ncsfpt = false; // ncsfpt on dom-path at this loop depth
2165 Node* nonlocal_ncsfpt = NULL; // ncsfpt on dom-path at a deeper depth
2166 // Scan the dom-path nodes from tail to head
2167 for (Node* n = tail(); n != _head; n = _phase->idom(n)) {
2168 if (n->is_Call() && n->as_Call()->guaranteed_safepoint()) {
2169 has_call = true;
2170 _has_sfpt = 1; // Then no need for a safept!
2171 break;
2172 } else if (n->Opcode() == Op_SafePoint) {
2173 if (_phase->get_loop(n) == this) {
2174 has_local_ncsfpt = true;
2175 break;
2176 }
2177 if (nonlocal_ncsfpt == NULL) {
2178 nonlocal_ncsfpt = n; // save the one closest to the tail
2179 }
2180 } else {
2181 IdealLoopTree* nlpt = _phase->get_loop(n);
2182 if (this != nlpt) {
2183 // If at an inner loop tail, see if the inner loop has already
2184 // recorded seeing a call on the dom-path (and stop.) If not,
2185 // jump to the head of the inner loop.
2186 assert(is_member(nlpt), "nested loop");
2187 Node* tail = nlpt->_tail;
2188 if (tail->in(0)->is_If()) tail = tail->in(0);
2189 if (n == tail) {
2190 // If inner loop has call on dom-path, so does outer loop
2191 if (nlpt->_has_sfpt) {
2192 has_call = true;
2193 _has_sfpt = 1;
2194 break;
2195 }
2196 // Skip to head of inner loop
2197 assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head");
2198 n = nlpt->_head;
2199 }
2200 }
2201 }
2202 }
2203 // Record safept's that this loop needs preserved when an
2204 // inner loop attempts to delete it's safepoints.
2205 if (_child != NULL && !has_call && !has_local_ncsfpt) {
2206 if (nonlocal_ncsfpt != NULL) {
2207 if (_required_safept == NULL) _required_safept = new Node_List();
2208 _required_safept->push(nonlocal_ncsfpt);
2209 } else {
2210 // Failed to find a suitable safept on the dom-path. Now use
2211 // an all paths walk from tail to head, looking for safepoints to preserve.
2212 allpaths_check_safepts(visited, stack);
2213 }
2214 }
2215 }
2216 }
2217
2218 //---------------------------is_deleteable_safept----------------------------
2219 // Is safept not required by an outer loop?
2220 bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) {
2221 assert(sfpt->Opcode() == Op_SafePoint, "");
2222 IdealLoopTree* lp = get_loop(sfpt)->_parent;
2223 while (lp != NULL) {
2224 Node_List* sfpts = lp->_required_safept;
2225 if (sfpts != NULL) {
2226 for (uint i = 0; i < sfpts->size(); i++) {
2227 if (sfpt == sfpts->at(i))
2228 return false;
2229 }
2230 }
2231 lp = lp->_parent;
2232 }
2233 return true;
2234 }
2235
2236 //---------------------------replace_parallel_iv-------------------------------
2237 // Replace parallel induction variable (parallel to trip counter)
2238 void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) {
2239 assert(loop->_head->is_CountedLoop(), "");
2240 CountedLoopNode *cl = loop->_head->as_CountedLoop();
2241 if (!cl->is_valid_counted_loop())
2242 return; // skip malformed counted loop
2243 Node *incr = cl->incr();
2244 if (incr == NULL)
2245 return; // Dead loop?
2246 Node *init = cl->init_trip();
2247 Node *phi = cl->phi();
2248 int stride_con = cl->stride_con();
2249
2250 // Visit all children, looking for Phis
2251 for (DUIterator i = cl->outs(); cl->has_out(i); i++) {
2252 Node *out = cl->out(i);
2253 // Look for other phis (secondary IVs). Skip dead ones
2254 if (!out->is_Phi() || out == phi || !has_node(out))
2255 continue;
2256 PhiNode* phi2 = out->as_Phi();
2257 Node *incr2 = phi2->in( LoopNode::LoopBackControl );
2258 // Look for induction variables of the form: X += constant
2259 if (phi2->region() != loop->_head ||
2260 incr2->req() != 3 ||
2261 incr2->in(1) != phi2 ||
2262 incr2 == incr ||
2263 incr2->Opcode() != Op_AddI ||
2264 !incr2->in(2)->is_Con())
2265 continue;
2266
2267 // Check for parallel induction variable (parallel to trip counter)
2268 // via an affine function. In particular, count-down loops with
2269 // count-up array indices are common. We only RCE references off
2270 // the trip-counter, so we need to convert all these to trip-counter
2271 // expressions.
2272 Node *init2 = phi2->in( LoopNode::EntryControl );
2273 int stride_con2 = incr2->in(2)->get_int();
2274
2275 // The ratio of the two strides cannot be represented as an int
2276 // if stride_con2 is min_int and stride_con is -1.
2277 if (stride_con2 == min_jint && stride_con == -1) {
2278 continue;
2279 }
2280
2281 // The general case here gets a little tricky. We want to find the
2282 // GCD of all possible parallel IV's and make a new IV using this
2283 // GCD for the loop. Then all possible IVs are simple multiples of
2284 // the GCD. In practice, this will cover very few extra loops.
2285 // Instead we require 'stride_con2' to be a multiple of 'stride_con',
2286 // where +/-1 is the common case, but other integer multiples are
2287 // also easy to handle.
2288 int ratio_con = stride_con2/stride_con;
2289
2290 if ((ratio_con * stride_con) == stride_con2) { // Check for exact
2291 #ifndef PRODUCT
2292 if (TraceLoopOpts) {
2293 tty->print("Parallel IV: %d ", phi2->_idx);
2294 loop->dump_head();
2295 }
2296 #endif
2297 // Convert to using the trip counter. The parallel induction
2298 // variable differs from the trip counter by a loop-invariant
2299 // amount, the difference between their respective initial values.
2300 // It is scaled by the 'ratio_con'.
2301 Node* ratio = _igvn.intcon(ratio_con);
2302 set_ctrl(ratio, C->root());
2303 Node* ratio_init = new MulINode(init, ratio);
2304 _igvn.register_new_node_with_optimizer(ratio_init, init);
2305 set_early_ctrl(ratio_init);
2306 Node* diff = new SubINode(init2, ratio_init);
2307 _igvn.register_new_node_with_optimizer(diff, init2);
2308 set_early_ctrl(diff);
2309 Node* ratio_idx = new MulINode(phi, ratio);
2310 _igvn.register_new_node_with_optimizer(ratio_idx, phi);
2311 set_ctrl(ratio_idx, cl);
2312 Node* add = new AddINode(ratio_idx, diff);
2313 _igvn.register_new_node_with_optimizer(add);
2314 set_ctrl(add, cl);
2315 _igvn.replace_node( phi2, add );
2316 // Sometimes an induction variable is unused
2317 if (add->outcnt() == 0) {
2318 _igvn.remove_dead_node(add);
2319 }
2320 --i; // deleted this phi; rescan starting with next position
2321 continue;
2322 }
2323 }
2324 }
2325
2326 void IdealLoopTree::remove_safepoints(PhaseIdealLoop* phase, bool keep_one) {
2327 Node* keep = NULL;
2328 if (keep_one) {
2329 // Look for a safepoint on the idom-path.
2330 for (Node* i = tail(); i != _head; i = phase->idom(i)) {
2331 if (i->Opcode() == Op_SafePoint && phase->get_loop(i) == this) {
2332 keep = i;
2333 break; // Found one
2334 }
2335 }
2336 }
2337
2338 // Don't remove any safepoints if it is requested to keep a single safepoint and
2339 // no safepoint was found on idom-path. It is not safe to remove any safepoint
2340 // in this case since there's no safepoint dominating all paths in the loop body.
2341 bool prune = !keep_one || keep != NULL;
2342
2343 // Delete other safepoints in this loop.
2344 Node_List* sfpts = _safepts;
2345 if (prune && sfpts != NULL) {
2346 assert(keep == NULL || keep->Opcode() == Op_SafePoint, "not safepoint");
2347 for (uint i = 0; i < sfpts->size(); i++) {
2348 Node* n = sfpts->at(i);
2349 assert(phase->get_loop(n) == this, "");
2350 if (n != keep && phase->is_deleteable_safept(n)) {
2351 phase->lazy_replace(n, n->in(TypeFunc::Control));
2352 }
2353 }
2354 }
2355 }
2356
2357 //------------------------------counted_loop-----------------------------------
2358 // Convert to counted loops where possible
2359 void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) {
2360
2361 // For grins, set the inner-loop flag here
2362 if (!_child) {
2363 if (_head->is_Loop()) _head->as_Loop()->set_inner_loop();
2364 }
2365
2366 IdealLoopTree* loop = this;
2367 if (_head->is_CountedLoop() ||
2368 phase->is_counted_loop(_head, loop)) {
2369
2370 if (LoopStripMiningIter == 0 || (LoopStripMiningIter > 1 && _child == NULL)) {
2371 // Indicate we do not need a safepoint here
2372 _has_sfpt = 1;
2373 }
2374
2375 // Remove safepoints
2376 bool keep_one_sfpt = !(_has_call || _has_sfpt);
2377 remove_safepoints(phase, keep_one_sfpt);
2378
2379 // Look for induction variables
2380 phase->replace_parallel_iv(this);
2381
2382 } else if (_parent != NULL && !_irreducible) {
2383 // Not a counted loop. Keep one safepoint.
2384 bool keep_one_sfpt = true;
2385 remove_safepoints(phase, keep_one_sfpt);
2386 }
2387
2388 // Recursively
2389 assert(loop->_child != this || (loop->_head->as_Loop()->is_OuterStripMinedLoop() && _head->as_CountedLoop()->is_strip_mined()), "what kind of loop was added?");
2390 assert(loop->_child != this || (loop->_child->_child == NULL && loop->_child->_next == NULL), "would miss some loops");
2391 if (loop->_child && loop->_child != this) loop->_child->counted_loop(phase);
2392 if (loop->_next) loop->_next ->counted_loop(phase);
2393 }
2394
2395 #ifndef PRODUCT
2396 //------------------------------dump_head--------------------------------------
2397 // Dump 1 liner for loop header info
2398 void IdealLoopTree::dump_head( ) const {
2399 for (uint i=0; i<_nest; i++)
2400 tty->print(" ");
2401 tty->print("Loop: N%d/N%d ",_head->_idx,_tail->_idx);
2402 if (_irreducible) tty->print(" IRREDUCIBLE");
2403 Node* entry = _head->is_Loop() ? _head->as_Loop()->skip_strip_mined(-1)->in(LoopNode::EntryControl) : _head->in(LoopNode::EntryControl);
2404 Node* predicate = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_loop_limit_check);
2405 if (predicate != NULL ) {
2406 tty->print(" limit_check");
2407 entry = entry->in(0)->in(0);
2408 }
2409 if (UseLoopPredicate) {
2410 entry = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_predicate);
2411 if (entry != NULL) {
2412 tty->print(" predicated");
2413 entry = PhaseIdealLoop::skip_loop_predicates(entry);
2414 }
2415 }
2416 if (UseProfiledLoopPredicate) {
2417 entry = PhaseIdealLoop::find_predicate_insertion_point(entry, Deoptimization::Reason_profile_predicate);
2418 if (entry != NULL) {
2419 tty->print(" profile_predicated");
2420 }
2421 }
2422 if (_head->is_CountedLoop()) {
2423 CountedLoopNode *cl = _head->as_CountedLoop();
2424 tty->print(" counted");
2425
2426 Node* init_n = cl->init_trip();
2427 if (init_n != NULL && init_n->is_Con())
2428 tty->print(" [%d,", cl->init_trip()->get_int());
2429 else
2430 tty->print(" [int,");
2431 Node* limit_n = cl->limit();
2432 if (limit_n != NULL && limit_n->is_Con())
2433 tty->print("%d),", cl->limit()->get_int());
2434 else
2435 tty->print("int),");
2436 int stride_con = cl->stride_con();
2437 if (stride_con > 0) tty->print("+");
2438 tty->print("%d", stride_con);
2439
2440 tty->print(" (%0.f iters) ", cl->profile_trip_cnt());
2441
2442 if (cl->is_pre_loop ()) tty->print(" pre" );
2443 if (cl->is_main_loop()) tty->print(" main");
2444 if (cl->is_post_loop()) tty->print(" post");
2445 if (cl->is_vectorized_loop()) tty->print(" vector");
2446 if (cl->range_checks_present()) tty->print(" rc ");
2447 if (cl->is_multiversioned()) tty->print(" multi ");
2448 }
2449 if (_has_call) tty->print(" has_call");
2450 if (_has_sfpt) tty->print(" has_sfpt");
2451 if (_rce_candidate) tty->print(" rce");
2452 if (_safepts != NULL && _safepts->size() > 0) {
2453 tty->print(" sfpts={"); _safepts->dump_simple(); tty->print(" }");
2454 }
2455 if (_required_safept != NULL && _required_safept->size() > 0) {
2456 tty->print(" req={"); _required_safept->dump_simple(); tty->print(" }");
2457 }
2458 if (Verbose) {
2459 tty->print(" body={"); _body.dump_simple(); tty->print(" }");
2460 }
2461 if (_head->is_Loop() && _head->as_Loop()->is_strip_mined()) {
2462 tty->print(" strip_mined");
2463 }
2464 tty->cr();
2465 }
2466
2467 //------------------------------dump-------------------------------------------
2468 // Dump loops by loop tree
2469 void IdealLoopTree::dump( ) const {
2470 dump_head();
2471 if (_child) _child->dump();
2472 if (_next) _next ->dump();
2473 }
2474
2475 #endif
2476
2477 static void log_loop_tree(IdealLoopTree* root, IdealLoopTree* loop, CompileLog* log) {
2478 if (loop == root) {
2479 if (loop->_child != NULL) {
2480 log->begin_head("loop_tree");
2481 log->end_head();
2482 if( loop->_child ) log_loop_tree(root, loop->_child, log);
2483 log->tail("loop_tree");
2484 assert(loop->_next == NULL, "what?");
2485 }
2486 } else {
2487 Node* head = loop->_head;
2488 log->begin_head("loop");
2489 log->print(" idx='%d' ", head->_idx);
2490 if (loop->_irreducible) log->print("irreducible='1' ");
2491 if (head->is_Loop()) {
2492 if (head->as_Loop()->is_inner_loop()) log->print("inner_loop='1' ");
2493 if (head->as_Loop()->is_partial_peel_loop()) log->print("partial_peel_loop='1' ");
2494 }
2495 if (head->is_CountedLoop()) {
2496 CountedLoopNode* cl = head->as_CountedLoop();
2497 if (cl->is_pre_loop()) log->print("pre_loop='%d' ", cl->main_idx());
2498 if (cl->is_main_loop()) log->print("main_loop='%d' ", cl->_idx);
2499 if (cl->is_post_loop()) log->print("post_loop='%d' ", cl->main_idx());
2500 }
2501 log->end_head();
2502 if( loop->_child ) log_loop_tree(root, loop->_child, log);
2503 log->tail("loop");
2504 if( loop->_next ) log_loop_tree(root, loop->_next, log);
2505 }
2506 }
2507
2508 //---------------------collect_potentially_useful_predicates-----------------------
2509 // Helper function to collect potentially useful predicates to prevent them from
2510 // being eliminated by PhaseIdealLoop::eliminate_useless_predicates
2511 void PhaseIdealLoop::collect_potentially_useful_predicates(
2512 IdealLoopTree * loop, Unique_Node_List &useful_predicates) {
2513 if (loop->_child) { // child
2514 collect_potentially_useful_predicates(loop->_child, useful_predicates);
2515 }
2516
2517 // self (only loops that we can apply loop predication may use their predicates)
2518 if (loop->_head->is_Loop() &&
2519 !loop->_irreducible &&
2520 !loop->tail()->is_top()) {
2521 LoopNode* lpn = loop->_head->as_Loop();
2522 Node* entry = lpn->in(LoopNode::EntryControl);
2523 Node* predicate_proj = find_predicate(entry); // loop_limit_check first
2524 if (predicate_proj != NULL ) { // right pattern that can be used by loop predication
2525 assert(entry->in(0)->in(1)->in(1)->Opcode() == Op_Opaque1, "must be");
2526 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
2527 entry = skip_loop_predicates(entry);
2528 }
2529 predicate_proj = find_predicate(entry); // Predicate
2530 if (predicate_proj != NULL ) {
2531 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
2532 entry = skip_loop_predicates(entry);
2533 }
2534 if (UseProfiledLoopPredicate) {
2535 predicate_proj = find_predicate(entry); // Predicate
2536 if (predicate_proj != NULL ) {
2537 useful_predicates.push(entry->in(0)->in(1)->in(1)); // good one
2538 }
2539 }
2540 }
2541
2542 if (loop->_next) { // sibling
2543 collect_potentially_useful_predicates(loop->_next, useful_predicates);
2544 }
2545 }
2546
2547 //------------------------eliminate_useless_predicates-----------------------------
2548 // Eliminate all inserted predicates if they could not be used by loop predication.
2549 // Note: it will also eliminates loop limits check predicate since it also uses
2550 // Opaque1 node (see Parse::add_predicate()).
2551 void PhaseIdealLoop::eliminate_useless_predicates() {
2552 if (C->predicate_count() == 0)
2553 return; // no predicate left
2554
2555 Unique_Node_List useful_predicates; // to store useful predicates
2556 if (C->has_loops()) {
2557 collect_potentially_useful_predicates(_ltree_root->_child, useful_predicates);
2558 }
2559
2560 for (int i = C->predicate_count(); i > 0; i--) {
2561 Node * n = C->predicate_opaque1_node(i-1);
2562 assert(n->Opcode() == Op_Opaque1, "must be");
2563 if (!useful_predicates.member(n)) { // not in the useful list
2564 _igvn.replace_node(n, n->in(1));
2565 }
2566 }
2567 }
2568
2569 //------------------------process_expensive_nodes-----------------------------
2570 // Expensive nodes have their control input set to prevent the GVN
2571 // from commoning them and as a result forcing the resulting node to
2572 // be in a more frequent path. Use CFG information here, to change the
2573 // control inputs so that some expensive nodes can be commoned while
2574 // not executed more frequently.
2575 bool PhaseIdealLoop::process_expensive_nodes() {
2576 assert(OptimizeExpensiveOps, "optimization off?");
2577
2578 // Sort nodes to bring similar nodes together
2579 C->sort_expensive_nodes();
2580
2581 bool progress = false;
2582
2583 for (int i = 0; i < C->expensive_count(); ) {
2584 Node* n = C->expensive_node(i);
2585 int start = i;
2586 // Find nodes similar to n
2587 i++;
2588 for (; i < C->expensive_count() && Compile::cmp_expensive_nodes(n, C->expensive_node(i)) == 0; i++);
2589 int end = i;
2590 // And compare them two by two
2591 for (int j = start; j < end; j++) {
2592 Node* n1 = C->expensive_node(j);
2593 if (is_node_unreachable(n1)) {
2594 continue;
2595 }
2596 for (int k = j+1; k < end; k++) {
2597 Node* n2 = C->expensive_node(k);
2598 if (is_node_unreachable(n2)) {
2599 continue;
2600 }
2601
2602 assert(n1 != n2, "should be pair of nodes");
2603
2604 Node* c1 = n1->in(0);
2605 Node* c2 = n2->in(0);
2606
2607 Node* parent_c1 = c1;
2608 Node* parent_c2 = c2;
2609
2610 // The call to get_early_ctrl_for_expensive() moves the
2611 // expensive nodes up but stops at loops that are in a if
2612 // branch. See whether we can exit the loop and move above the
2613 // If.
2614 if (c1->is_Loop()) {
2615 parent_c1 = c1->in(1);
2616 }
2617 if (c2->is_Loop()) {
2618 parent_c2 = c2->in(1);
2619 }
2620
2621 if (parent_c1 == parent_c2) {
2622 _igvn._worklist.push(n1);
2623 _igvn._worklist.push(n2);
2624 continue;
2625 }
2626
2627 // Look for identical expensive node up the dominator chain.
2628 if (is_dominator(c1, c2)) {
2629 c2 = c1;
2630 } else if (is_dominator(c2, c1)) {
2631 c1 = c2;
2632 } else if (parent_c1->is_Proj() && parent_c1->in(0)->is_If() &&
2633 parent_c2->is_Proj() && parent_c1->in(0) == parent_c2->in(0)) {
2634 // Both branches have the same expensive node so move it up
2635 // before the if.
2636 c1 = c2 = idom(parent_c1->in(0));
2637 }
2638 // Do the actual moves
2639 if (n1->in(0) != c1) {
2640 _igvn.hash_delete(n1);
2641 n1->set_req(0, c1);
2642 _igvn.hash_insert(n1);
2643 _igvn._worklist.push(n1);
2644 progress = true;
2645 }
2646 if (n2->in(0) != c2) {
2647 _igvn.hash_delete(n2);
2648 n2->set_req(0, c2);
2649 _igvn.hash_insert(n2);
2650 _igvn._worklist.push(n2);
2651 progress = true;
2652 }
2653 }
2654 }
2655 }
2656
2657 return progress;
2658 }
2659
2660
2661 //=============================================================================
2662 //----------------------------build_and_optimize-------------------------------
2663 // Create a PhaseLoop. Build the ideal Loop tree. Map each Ideal Node to
2664 // its corresponding LoopNode. If 'optimize' is true, do some loop cleanups.
2665 void PhaseIdealLoop::build_and_optimize(LoopOptsMode mode) {
2666 bool do_split_ifs = (mode == LoopOptsDefault || mode == LoopOptsLastRound);
2667 bool skip_loop_opts = (mode == LoopOptsNone);
2668
2669 ResourceMark rm;
2670
2671 int old_progress = C->major_progress();
2672 uint orig_worklist_size = _igvn._worklist.size();
2673
2674 // Reset major-progress flag for the driver's heuristics
2675 C->clear_major_progress();
2676
2677 #ifndef PRODUCT
2678 // Capture for later assert
2679 uint unique = C->unique();
2680 _loop_invokes++;
2681 _loop_work += unique;
2682 #endif
2683
2684 // True if the method has at least 1 irreducible loop
2685 _has_irreducible_loops = false;
2686
2687 _created_loop_node = false;
2688
2689 Arena *a = Thread::current()->resource_area();
2690 VectorSet visited(a);
2691 // Pre-grow the mapping from Nodes to IdealLoopTrees.
2692 _nodes.map(C->unique(), NULL);
2693 memset(_nodes.adr(), 0, wordSize * C->unique());
2694
2695 // Pre-build the top-level outermost loop tree entry
2696 _ltree_root = new IdealLoopTree( this, C->root(), C->root() );
2697 // Do not need a safepoint at the top level
2698 _ltree_root->_has_sfpt = 1;
2699
2700 // Initialize Dominators.
2701 // Checked in clone_loop_predicate() during beautify_loops().
2702 _idom_size = 0;
2703 _idom = NULL;
2704 _dom_depth = NULL;
2705 _dom_stk = NULL;
2706
2707 // Empty pre-order array
2708 allocate_preorders();
2709
2710 // Build a loop tree on the fly. Build a mapping from CFG nodes to
2711 // IdealLoopTree entries. Data nodes are NOT walked.
2712 build_loop_tree();
2713 // Check for bailout, and return
2714 if (C->failing()) {
2715 return;
2716 }
2717
2718 // No loops after all
2719 if( !_ltree_root->_child && !_verify_only ) C->set_has_loops(false);
2720
2721 // There should always be an outer loop containing the Root and Return nodes.
2722 // If not, we have a degenerate empty program. Bail out in this case.
2723 if (!has_node(C->root())) {
2724 if (!_verify_only) {
2725 C->clear_major_progress();
2726 C->record_method_not_compilable("empty program detected during loop optimization");
2727 }
2728 return;
2729 }
2730
2731 // Nothing to do, so get out
2732 bool stop_early = !C->has_loops() && !skip_loop_opts && !do_split_ifs && !_verify_me && !_verify_only;
2733 bool do_expensive_nodes = C->should_optimize_expensive_nodes(_igvn);
2734 if (stop_early && !do_expensive_nodes) {
2735 _igvn.optimize(); // Cleanup NeverBranches
2736 return;
2737 }
2738
2739 // Set loop nesting depth
2740 _ltree_root->set_nest( 0 );
2741
2742 // Split shared headers and insert loop landing pads.
2743 // Do not bother doing this on the Root loop of course.
2744 if( !_verify_me && !_verify_only && _ltree_root->_child ) {
2745 C->print_method(PHASE_BEFORE_BEAUTIFY_LOOPS, 3);
2746 if( _ltree_root->_child->beautify_loops( this ) ) {
2747 // Re-build loop tree!
2748 _ltree_root->_child = NULL;
2749 _nodes.clear();
2750 reallocate_preorders();
2751 build_loop_tree();
2752 // Check for bailout, and return
2753 if (C->failing()) {
2754 return;
2755 }
2756 // Reset loop nesting depth
2757 _ltree_root->set_nest( 0 );
2758
2759 C->print_method(PHASE_AFTER_BEAUTIFY_LOOPS, 3);
2760 }
2761 }
2762
2763 // Build Dominators for elision of NULL checks & loop finding.
2764 // Since nodes do not have a slot for immediate dominator, make
2765 // a persistent side array for that info indexed on node->_idx.
2766 _idom_size = C->unique();
2767 _idom = NEW_RESOURCE_ARRAY( Node*, _idom_size );
2768 _dom_depth = NEW_RESOURCE_ARRAY( uint, _idom_size );
2769 _dom_stk = NULL; // Allocated on demand in recompute_dom_depth
2770 memset( _dom_depth, 0, _idom_size * sizeof(uint) );
2771
2772 Dominators();
2773
2774 if (!_verify_only) {
2775 // As a side effect, Dominators removed any unreachable CFG paths
2776 // into RegionNodes. It doesn't do this test against Root, so
2777 // we do it here.
2778 for( uint i = 1; i < C->root()->req(); i++ ) {
2779 if( !_nodes[C->root()->in(i)->_idx] ) { // Dead path into Root?
2780 _igvn.delete_input_of(C->root(), i);
2781 i--; // Rerun same iteration on compressed edges
2782 }
2783 }
2784
2785 // Given dominators, try to find inner loops with calls that must
2786 // always be executed (call dominates loop tail). These loops do
2787 // not need a separate safepoint.
2788 Node_List cisstack(a);
2789 _ltree_root->check_safepts(visited, cisstack);
2790 }
2791
2792 // Walk the DATA nodes and place into loops. Find earliest control
2793 // node. For CFG nodes, the _nodes array starts out and remains
2794 // holding the associated IdealLoopTree pointer. For DATA nodes, the
2795 // _nodes array holds the earliest legal controlling CFG node.
2796
2797 // Allocate stack with enough space to avoid frequent realloc
2798 int stack_size = (C->live_nodes() >> 1) + 16; // (live_nodes>>1)+16 from Java2D stats
2799 Node_Stack nstack( a, stack_size );
2800
2801 visited.Clear();
2802 Node_List worklist(a);
2803 // Don't need C->root() on worklist since
2804 // it will be processed among C->top() inputs
2805 worklist.push( C->top() );
2806 visited.set( C->top()->_idx ); // Set C->top() as visited now
2807 build_loop_early( visited, worklist, nstack );
2808
2809 // Given early legal placement, try finding counted loops. This placement
2810 // is good enough to discover most loop invariants.
2811 if( !_verify_me && !_verify_only )
2812 _ltree_root->counted_loop( this );
2813
2814 // Find latest loop placement. Find ideal loop placement.
2815 visited.Clear();
2816 init_dom_lca_tags();
2817 // Need C->root() on worklist when processing outs
2818 worklist.push( C->root() );
2819 NOT_PRODUCT( C->verify_graph_edges(); )
2820 worklist.push( C->top() );
2821 build_loop_late( visited, worklist, nstack );
2822
2823 if (_verify_only) {
2824 // restore major progress flag
2825 for (int i = 0; i < old_progress; i++)
2826 C->set_major_progress();
2827 assert(C->unique() == unique, "verification mode made Nodes? ? ?");
2828 assert(_igvn._worklist.size() == orig_worklist_size, "shouldn't push anything");
2829 return;
2830 }
2831
2832 // clear out the dead code after build_loop_late
2833 while (_deadlist.size()) {
2834 _igvn.remove_globally_dead_node(_deadlist.pop());
2835 }
2836
2837 if (stop_early) {
2838 assert(do_expensive_nodes, "why are we here?");
2839 if (process_expensive_nodes()) {
2840 // If we made some progress when processing expensive nodes then
2841 // the IGVN may modify the graph in a way that will allow us to
2842 // make some more progress: we need to try processing expensive
2843 // nodes again.
2844 C->set_major_progress();
2845 }
2846 _igvn.optimize();
2847 return;
2848 }
2849
2850 // Some parser-inserted loop predicates could never be used by loop
2851 // predication or they were moved away from loop during some optimizations.
2852 // For example, peeling. Eliminate them before next loop optimizations.
2853 eliminate_useless_predicates();
2854
2855 #ifndef PRODUCT
2856 C->verify_graph_edges();
2857 if (_verify_me) { // Nested verify pass?
2858 // Check to see if the verify mode is broken
2859 assert(C->unique() == unique, "non-optimize mode made Nodes? ? ?");
2860 return;
2861 }
2862 if(VerifyLoopOptimizations) verify();
2863 if(TraceLoopOpts && C->has_loops()) {
2864 _ltree_root->dump();
2865 }
2866 #endif
2867
2868 if (skip_loop_opts) {
2869 // restore major progress flag
2870 for (int i = 0; i < old_progress; i++) {
2871 C->set_major_progress();
2872 }
2873
2874 // Cleanup any modified bits
2875 _igvn.optimize();
2876
2877 if (C->log() != NULL) {
2878 log_loop_tree(_ltree_root, _ltree_root, C->log());
2879 }
2880 return;
2881 }
2882
2883 if (ReassociateInvariants) {
2884 // Reassociate invariants and prep for split_thru_phi
2885 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2886 IdealLoopTree* lpt = iter.current();
2887 bool is_counted = lpt->is_counted();
2888 if (!is_counted || !lpt->is_inner()) continue;
2889
2890 // check for vectorized loops, any reassociation of invariants was already done
2891 if (is_counted && lpt->_head->as_CountedLoop()->do_unroll_only()) continue;
2892
2893 lpt->reassociate_invariants(this);
2894
2895 // Because RCE opportunities can be masked by split_thru_phi,
2896 // look for RCE candidates and inhibit split_thru_phi
2897 // on just their loop-phi's for this pass of loop opts
2898 if (SplitIfBlocks && do_split_ifs) {
2899 if (lpt->policy_range_check(this)) {
2900 lpt->_rce_candidate = 1; // = true
2901 }
2902 }
2903 }
2904 }
2905
2906 // Check for aggressive application of split-if and other transforms
2907 // that require basic-block info (like cloning through Phi's)
2908 if( SplitIfBlocks && do_split_ifs ) {
2909 visited.Clear();
2910 split_if_with_blocks( visited, nstack, mode == LoopOptsLastRound );
2911 NOT_PRODUCT( if( VerifyLoopOptimizations ) verify(); );
2912 if (mode == LoopOptsLastRound) {
2913 C->set_major_progress();
2914 }
2915 }
2916
2917 if (!C->major_progress() && do_expensive_nodes && process_expensive_nodes()) {
2918 C->set_major_progress();
2919 }
2920
2921 // Perform loop predication before iteration splitting
2922 if (C->has_loops() && !C->major_progress() && (C->predicate_count() > 0)) {
2923 _ltree_root->_child->loop_predication(this);
2924 }
2925
2926 if (OptimizeFill && UseLoopPredicate && C->has_loops() && !C->major_progress()) {
2927 if (do_intrinsify_fill()) {
2928 C->set_major_progress();
2929 }
2930 }
2931
2932 // Perform iteration-splitting on inner loops. Split iterations to avoid
2933 // range checks or one-shot null checks.
2934
2935 // If split-if's didn't hack the graph too bad (no CFG changes)
2936 // then do loop opts.
2937 if (C->has_loops() && !C->major_progress()) {
2938 memset( worklist.adr(), 0, worklist.Size()*sizeof(Node*) );
2939 _ltree_root->_child->iteration_split( this, worklist );
2940 // No verify after peeling! GCM has hoisted code out of the loop.
2941 // After peeling, the hoisted code could sink inside the peeled area.
2942 // The peeling code does not try to recompute the best location for
2943 // all the code before the peeled area, so the verify pass will always
2944 // complain about it.
2945 }
2946 // Do verify graph edges in any case
2947 NOT_PRODUCT( C->verify_graph_edges(); );
2948
2949 if (!do_split_ifs) {
2950 // We saw major progress in Split-If to get here. We forced a
2951 // pass with unrolling and not split-if, however more split-if's
2952 // might make progress. If the unrolling didn't make progress
2953 // then the major-progress flag got cleared and we won't try
2954 // another round of Split-If. In particular the ever-common
2955 // instance-of/check-cast pattern requires at least 2 rounds of
2956 // Split-If to clear out.
2957 C->set_major_progress();
2958 }
2959
2960 // Repeat loop optimizations if new loops were seen
2961 if (created_loop_node()) {
2962 C->set_major_progress();
2963 }
2964
2965 // Keep loop predicates and perform optimizations with them
2966 // until no more loop optimizations could be done.
2967 // After that switch predicates off and do more loop optimizations.
2968 if (!C->major_progress() && (C->predicate_count() > 0)) {
2969 C->cleanup_loop_predicates(_igvn);
2970 if (TraceLoopOpts) {
2971 tty->print_cr("PredicatesOff");
2972 }
2973 C->set_major_progress();
2974 }
2975
2976 // Convert scalar to superword operations at the end of all loop opts.
2977 if (UseSuperWord && C->has_loops() && !C->major_progress()) {
2978 // SuperWord transform
2979 SuperWord sw(this);
2980 for (LoopTreeIterator iter(_ltree_root); !iter.done(); iter.next()) {
2981 IdealLoopTree* lpt = iter.current();
2982 if (lpt->is_counted()) {
2983 CountedLoopNode *cl = lpt->_head->as_CountedLoop();
2984
2985 if (PostLoopMultiversioning && cl->is_rce_post_loop() && !cl->is_vectorized_loop()) {
2986 // Check that the rce'd post loop is encountered first, multiversion after all
2987 // major main loop optimization are concluded
2988 if (!C->major_progress()) {
2989 IdealLoopTree *lpt_next = lpt->_next;
2990 if (lpt_next && lpt_next->is_counted()) {
2991 CountedLoopNode *cl = lpt_next->_head->as_CountedLoop();
2992 has_range_checks(lpt_next);
2993 if (cl->is_post_loop() && cl->range_checks_present()) {
2994 if (!cl->is_multiversioned()) {
2995 if (multi_version_post_loops(lpt, lpt_next) == false) {
2996 // Cause the rce loop to be optimized away if we fail
2997 cl->mark_is_multiversioned();
2998 cl->set_slp_max_unroll(0);
2999 poison_rce_post_loop(lpt);
3000 }
3001 }
3002 }
3003 }
3004 sw.transform_loop(lpt, true);
3005 }
3006 } else if (cl->is_main_loop()) {
3007 sw.transform_loop(lpt, true);
3008 }
3009 }
3010 }
3011 }
3012
3013 // Cleanup any modified bits
3014 _igvn.optimize();
3015
3016 // disable assert until issue with split_flow_path is resolved (6742111)
3017 // assert(!_has_irreducible_loops || C->parsed_irreducible_loop() || C->is_osr_compilation(),
3018 // "shouldn't introduce irreducible loops");
3019
3020 if (C->log() != NULL) {
3021 log_loop_tree(_ltree_root, _ltree_root, C->log());
3022 }
3023 }
3024
3025 #ifndef PRODUCT
3026 //------------------------------print_statistics-------------------------------
3027 int PhaseIdealLoop::_loop_invokes=0;// Count of PhaseIdealLoop invokes
3028 int PhaseIdealLoop::_loop_work=0; // Sum of PhaseIdealLoop x unique
3029 void PhaseIdealLoop::print_statistics() {
3030 tty->print_cr("PhaseIdealLoop=%d, sum _unique=%d", _loop_invokes, _loop_work);
3031 }
3032
3033 //------------------------------verify-----------------------------------------
3034 // Build a verify-only PhaseIdealLoop, and see that it agrees with me.
3035 static int fail; // debug only, so its multi-thread dont care
3036 void PhaseIdealLoop::verify() const {
3037 int old_progress = C->major_progress();
3038 ResourceMark rm;
3039 PhaseIdealLoop loop_verify( _igvn, this );
3040 VectorSet visited(Thread::current()->resource_area());
3041
3042 fail = 0;
3043 verify_compare( C->root(), &loop_verify, visited );
3044 assert( fail == 0, "verify loops failed" );
3045 // Verify loop structure is the same
3046 _ltree_root->verify_tree(loop_verify._ltree_root, NULL);
3047 // Reset major-progress. It was cleared by creating a verify version of
3048 // PhaseIdealLoop.
3049 for( int i=0; i<old_progress; i++ )
3050 C->set_major_progress();
3051 }
3052
3053 //------------------------------verify_compare---------------------------------
3054 // Make sure me and the given PhaseIdealLoop agree on key data structures
3055 void PhaseIdealLoop::verify_compare( Node *n, const PhaseIdealLoop *loop_verify, VectorSet &visited ) const {
3056 if( !n ) return;
3057 if( visited.test_set( n->_idx ) ) return;
3058 if( !_nodes[n->_idx] ) { // Unreachable
3059 assert( !loop_verify->_nodes[n->_idx], "both should be unreachable" );
3060 return;
3061 }
3062
3063 uint i;
3064 for( i = 0; i < n->req(); i++ )
3065 verify_compare( n->in(i), loop_verify, visited );
3066
3067 // Check the '_nodes' block/loop structure
3068 i = n->_idx;
3069 if( has_ctrl(n) ) { // We have control; verify has loop or ctrl
3070 if( _nodes[i] != loop_verify->_nodes[i] &&
3071 get_ctrl_no_update(n) != loop_verify->get_ctrl_no_update(n) ) {
3072 tty->print("Mismatched control setting for: ");
3073 n->dump();
3074 if( fail++ > 10 ) return;
3075 Node *c = get_ctrl_no_update(n);
3076 tty->print("We have it as: ");
3077 if( c->in(0) ) c->dump();
3078 else tty->print_cr("N%d",c->_idx);
3079 tty->print("Verify thinks: ");
3080 if( loop_verify->has_ctrl(n) )
3081 loop_verify->get_ctrl_no_update(n)->dump();
3082 else
3083 loop_verify->get_loop_idx(n)->dump();
3084 tty->cr();
3085 }
3086 } else { // We have a loop
3087 IdealLoopTree *us = get_loop_idx(n);
3088 if( loop_verify->has_ctrl(n) ) {
3089 tty->print("Mismatched loop setting for: ");
3090 n->dump();
3091 if( fail++ > 10 ) return;
3092 tty->print("We have it as: ");
3093 us->dump();
3094 tty->print("Verify thinks: ");
3095 loop_verify->get_ctrl_no_update(n)->dump();
3096 tty->cr();
3097 } else if (!C->major_progress()) {
3098 // Loop selection can be messed up if we did a major progress
3099 // operation, like split-if. Do not verify in that case.
3100 IdealLoopTree *them = loop_verify->get_loop_idx(n);
3101 if( us->_head != them->_head || us->_tail != them->_tail ) {
3102 tty->print("Unequals loops for: ");
3103 n->dump();
3104 if( fail++ > 10 ) return;
3105 tty->print("We have it as: ");
3106 us->dump();
3107 tty->print("Verify thinks: ");
3108 them->dump();
3109 tty->cr();
3110 }
3111 }
3112 }
3113
3114 // Check for immediate dominators being equal
3115 if( i >= _idom_size ) {
3116 if( !n->is_CFG() ) return;
3117 tty->print("CFG Node with no idom: ");
3118 n->dump();
3119 return;
3120 }
3121 if( !n->is_CFG() ) return;
3122 if( n == C->root() ) return; // No IDOM here
3123
3124 assert(n->_idx == i, "sanity");
3125 Node *id = idom_no_update(n);
3126 if( id != loop_verify->idom_no_update(n) ) {
3127 tty->print("Unequals idoms for: ");
3128 n->dump();
3129 if( fail++ > 10 ) return;
3130 tty->print("We have it as: ");
3131 id->dump();
3132 tty->print("Verify thinks: ");
3133 loop_verify->idom_no_update(n)->dump();
3134 tty->cr();
3135 }
3136
3137 }
3138
3139 //------------------------------verify_tree------------------------------------
3140 // Verify that tree structures match. Because the CFG can change, siblings
3141 // within the loop tree can be reordered. We attempt to deal with that by
3142 // reordering the verify's loop tree if possible.
3143 void IdealLoopTree::verify_tree(IdealLoopTree *loop, const IdealLoopTree *parent) const {
3144 assert( _parent == parent, "Badly formed loop tree" );
3145
3146 // Siblings not in same order? Attempt to re-order.
3147 if( _head != loop->_head ) {
3148 // Find _next pointer to update
3149 IdealLoopTree **pp = &loop->_parent->_child;
3150 while( *pp != loop )
3151 pp = &((*pp)->_next);
3152 // Find proper sibling to be next
3153 IdealLoopTree **nn = &loop->_next;
3154 while( (*nn) && (*nn)->_head != _head )
3155 nn = &((*nn)->_next);
3156
3157 // Check for no match.
3158 if( !(*nn) ) {
3159 // Annoyingly, irreducible loops can pick different headers
3160 // after a major_progress operation, so the rest of the loop
3161 // tree cannot be matched.
3162 if (_irreducible && Compile::current()->major_progress()) return;
3163 assert( 0, "failed to match loop tree" );
3164 }
3165
3166 // Move (*nn) to (*pp)
3167 IdealLoopTree *hit = *nn;
3168 *nn = hit->_next;
3169 hit->_next = loop;
3170 *pp = loop;
3171 loop = hit;
3172 // Now try again to verify
3173 }
3174
3175 assert( _head == loop->_head , "mismatched loop head" );
3176 Node *tail = _tail; // Inline a non-updating version of
3177 while( !tail->in(0) ) // the 'tail()' call.
3178 tail = tail->in(1);
3179 assert( tail == loop->_tail, "mismatched loop tail" );
3180
3181 // Counted loops that are guarded should be able to find their guards
3182 if( _head->is_CountedLoop() && _head->as_CountedLoop()->is_main_loop() ) {
3183 CountedLoopNode *cl = _head->as_CountedLoop();
3184 Node *init = cl->init_trip();
3185 Node *ctrl = cl->in(LoopNode::EntryControl);
3186 assert( ctrl->Opcode() == Op_IfTrue || ctrl->Opcode() == Op_IfFalse, "" );
3187 Node *iff = ctrl->in(0);
3188 assert( iff->Opcode() == Op_If, "" );
3189 Node *bol = iff->in(1);
3190 assert( bol->Opcode() == Op_Bool, "" );
3191 Node *cmp = bol->in(1);
3192 assert( cmp->Opcode() == Op_CmpI, "" );
3193 Node *add = cmp->in(1);
3194 Node *opaq;
3195 if( add->Opcode() == Op_Opaque1 ) {
3196 opaq = add;
3197 } else {
3198 assert( add->Opcode() == Op_AddI || add->Opcode() == Op_ConI , "" );
3199 assert( add == init, "" );
3200 opaq = cmp->in(2);
3201 }
3202 assert( opaq->Opcode() == Op_Opaque1, "" );
3203
3204 }
3205
3206 if (_child != NULL) _child->verify_tree(loop->_child, this);
3207 if (_next != NULL) _next ->verify_tree(loop->_next, parent);
3208 // Innermost loops need to verify loop bodies,
3209 // but only if no 'major_progress'
3210 int fail = 0;
3211 if (!Compile::current()->major_progress() && _child == NULL) {
3212 for( uint i = 0; i < _body.size(); i++ ) {
3213 Node *n = _body.at(i);
3214 if (n->outcnt() == 0) continue; // Ignore dead
3215 uint j;
3216 for( j = 0; j < loop->_body.size(); j++ )
3217 if( loop->_body.at(j) == n )
3218 break;
3219 if( j == loop->_body.size() ) { // Not found in loop body
3220 // Last ditch effort to avoid assertion: Its possible that we
3221 // have some users (so outcnt not zero) but are still dead.
3222 // Try to find from root.
3223 if (Compile::current()->root()->find(n->_idx)) {
3224 fail++;
3225 tty->print("We have that verify does not: ");
3226 n->dump();
3227 }
3228 }
3229 }
3230 for( uint i2 = 0; i2 < loop->_body.size(); i2++ ) {
3231 Node *n = loop->_body.at(i2);
3232 if (n->outcnt() == 0) continue; // Ignore dead
3233 uint j;
3234 for( j = 0; j < _body.size(); j++ )
3235 if( _body.at(j) == n )
3236 break;
3237 if( j == _body.size() ) { // Not found in loop body
3238 // Last ditch effort to avoid assertion: Its possible that we
3239 // have some users (so outcnt not zero) but are still dead.
3240 // Try to find from root.
3241 if (Compile::current()->root()->find(n->_idx)) {
3242 fail++;
3243 tty->print("Verify has that we do not: ");
3244 n->dump();
3245 }
3246 }
3247 }
3248 assert( !fail, "loop body mismatch" );
3249 }
3250 }
3251
3252 #endif
3253
3254 //------------------------------set_idom---------------------------------------
3255 void PhaseIdealLoop::set_idom(Node* d, Node* n, uint dom_depth) {
3256 uint idx = d->_idx;
3257 if (idx >= _idom_size) {
3258 uint newsize = _idom_size<<1;
3259 while( idx >= newsize ) {
3260 newsize <<= 1;
3261 }
3262 _idom = REALLOC_RESOURCE_ARRAY( Node*, _idom,_idom_size,newsize);
3263 _dom_depth = REALLOC_RESOURCE_ARRAY( uint, _dom_depth,_idom_size,newsize);
3264 memset( _dom_depth + _idom_size, 0, (newsize - _idom_size) * sizeof(uint) );
3265 _idom_size = newsize;
3266 }
3267 _idom[idx] = n;
3268 _dom_depth[idx] = dom_depth;
3269 }
3270
3271 //------------------------------recompute_dom_depth---------------------------------------
3272 // The dominator tree is constructed with only parent pointers.
3273 // This recomputes the depth in the tree by first tagging all
3274 // nodes as "no depth yet" marker. The next pass then runs up
3275 // the dom tree from each node marked "no depth yet", and computes
3276 // the depth on the way back down.
3277 void PhaseIdealLoop::recompute_dom_depth() {
3278 uint no_depth_marker = C->unique();
3279 uint i;
3280 // Initialize depth to "no depth yet" and realize all lazy updates
3281 for (i = 0; i < _idom_size; i++) {
3282 // Only indices with a _dom_depth has a Node* or NULL (otherwise uninitalized).
3283 if (_dom_depth[i] > 0 && _idom[i] != NULL) {
3284 _dom_depth[i] = no_depth_marker;
3285
3286 // heal _idom if it has a fwd mapping in _nodes
3287 if (_idom[i]->in(0) == NULL) {
3288 idom(i);
3289 }
3290 }
3291 }
3292 if (_dom_stk == NULL) {
3293 uint init_size = C->live_nodes() / 100; // Guess that 1/100 is a reasonable initial size.
3294 if (init_size < 10) init_size = 10;
3295 _dom_stk = new GrowableArray<uint>(init_size);
3296 }
3297 // Compute new depth for each node.
3298 for (i = 0; i < _idom_size; i++) {
3299 uint j = i;
3300 // Run up the dom tree to find a node with a depth
3301 while (_dom_depth[j] == no_depth_marker) {
3302 _dom_stk->push(j);
3303 j = _idom[j]->_idx;
3304 }
3305 // Compute the depth on the way back down this tree branch
3306 uint dd = _dom_depth[j] + 1;
3307 while (_dom_stk->length() > 0) {
3308 uint j = _dom_stk->pop();
3309 _dom_depth[j] = dd;
3310 dd++;
3311 }
3312 }
3313 }
3314
3315 //------------------------------sort-------------------------------------------
3316 // Insert 'loop' into the existing loop tree. 'innermost' is a leaf of the
3317 // loop tree, not the root.
3318 IdealLoopTree *PhaseIdealLoop::sort( IdealLoopTree *loop, IdealLoopTree *innermost ) {
3319 if( !innermost ) return loop; // New innermost loop
3320
3321 int loop_preorder = get_preorder(loop->_head); // Cache pre-order number
3322 assert( loop_preorder, "not yet post-walked loop" );
3323 IdealLoopTree **pp = &innermost; // Pointer to previous next-pointer
3324 IdealLoopTree *l = *pp; // Do I go before or after 'l'?
3325
3326 // Insert at start of list
3327 while( l ) { // Insertion sort based on pre-order
3328 if( l == loop ) return innermost; // Already on list!
3329 int l_preorder = get_preorder(l->_head); // Cache pre-order number
3330 assert( l_preorder, "not yet post-walked l" );
3331 // Check header pre-order number to figure proper nesting
3332 if( loop_preorder > l_preorder )
3333 break; // End of insertion
3334 // If headers tie (e.g., shared headers) check tail pre-order numbers.
3335 // Since I split shared headers, you'd think this could not happen.
3336 // BUT: I must first do the preorder numbering before I can discover I
3337 // have shared headers, so the split headers all get the same preorder
3338 // number as the RegionNode they split from.
3339 if( loop_preorder == l_preorder &&
3340 get_preorder(loop->_tail) < get_preorder(l->_tail) )
3341 break; // Also check for shared headers (same pre#)
3342 pp = &l->_parent; // Chain up list
3343 l = *pp;
3344 }
3345 // Link into list
3346 // Point predecessor to me
3347 *pp = loop;
3348 // Point me to successor
3349 IdealLoopTree *p = loop->_parent;
3350 loop->_parent = l; // Point me to successor
3351 if( p ) sort( p, innermost ); // Insert my parents into list as well
3352 return innermost;
3353 }
3354
3355 //------------------------------build_loop_tree--------------------------------
3356 // I use a modified Vick/Tarjan algorithm. I need pre- and a post- visit
3357 // bits. The _nodes[] array is mapped by Node index and holds a NULL for
3358 // not-yet-pre-walked, pre-order # for pre-but-not-post-walked and holds the
3359 // tightest enclosing IdealLoopTree for post-walked.
3360 //
3361 // During my forward walk I do a short 1-layer lookahead to see if I can find
3362 // a loop backedge with that doesn't have any work on the backedge. This
3363 // helps me construct nested loops with shared headers better.
3364 //
3365 // Once I've done the forward recursion, I do the post-work. For each child
3366 // I check to see if there is a backedge. Backedges define a loop! I
3367 // insert an IdealLoopTree at the target of the backedge.
3368 //
3369 // During the post-work I also check to see if I have several children
3370 // belonging to different loops. If so, then this Node is a decision point
3371 // where control flow can choose to change loop nests. It is at this
3372 // decision point where I can figure out how loops are nested. At this
3373 // time I can properly order the different loop nests from my children.
3374 // Note that there may not be any backedges at the decision point!
3375 //
3376 // Since the decision point can be far removed from the backedges, I can't
3377 // order my loops at the time I discover them. Thus at the decision point
3378 // I need to inspect loop header pre-order numbers to properly nest my
3379 // loops. This means I need to sort my childrens' loops by pre-order.
3380 // The sort is of size number-of-control-children, which generally limits
3381 // it to size 2 (i.e., I just choose between my 2 target loops).
3382 void PhaseIdealLoop::build_loop_tree() {
3383 // Allocate stack of size C->live_nodes()/2 to avoid frequent realloc
3384 GrowableArray <Node *> bltstack(C->live_nodes() >> 1);
3385 Node *n = C->root();
3386 bltstack.push(n);
3387 int pre_order = 1;
3388 int stack_size;
3389
3390 while ( ( stack_size = bltstack.length() ) != 0 ) {
3391 n = bltstack.top(); // Leave node on stack
3392 if ( !is_visited(n) ) {
3393 // ---- Pre-pass Work ----
3394 // Pre-walked but not post-walked nodes need a pre_order number.
3395
3396 set_preorder_visited( n, pre_order ); // set as visited
3397
3398 // ---- Scan over children ----
3399 // Scan first over control projections that lead to loop headers.
3400 // This helps us find inner-to-outer loops with shared headers better.
3401
3402 // Scan children's children for loop headers.
3403 for ( int i = n->outcnt() - 1; i >= 0; --i ) {
3404 Node* m = n->raw_out(i); // Child
3405 if( m->is_CFG() && !is_visited(m) ) { // Only for CFG children
3406 // Scan over children's children to find loop
3407 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3408 Node* l = m->fast_out(j);
3409 if( is_visited(l) && // Been visited?
3410 !is_postvisited(l) && // But not post-visited
3411 get_preorder(l) < pre_order ) { // And smaller pre-order
3412 // Found! Scan the DFS down this path before doing other paths
3413 bltstack.push(m);
3414 break;
3415 }
3416 }
3417 }
3418 }
3419 pre_order++;
3420 }
3421 else if ( !is_postvisited(n) ) {
3422 // Note: build_loop_tree_impl() adds out edges on rare occasions,
3423 // such as com.sun.rsasign.am::a.
3424 // For non-recursive version, first, process current children.
3425 // On next iteration, check if additional children were added.
3426 for ( int k = n->outcnt() - 1; k >= 0; --k ) {
3427 Node* u = n->raw_out(k);
3428 if ( u->is_CFG() && !is_visited(u) ) {
3429 bltstack.push(u);
3430 }
3431 }
3432 if ( bltstack.length() == stack_size ) {
3433 // There were no additional children, post visit node now
3434 (void)bltstack.pop(); // Remove node from stack
3435 pre_order = build_loop_tree_impl( n, pre_order );
3436 // Check for bailout
3437 if (C->failing()) {
3438 return;
3439 }
3440 // Check to grow _preorders[] array for the case when
3441 // build_loop_tree_impl() adds new nodes.
3442 check_grow_preorders();
3443 }
3444 }
3445 else {
3446 (void)bltstack.pop(); // Remove post-visited node from stack
3447 }
3448 }
3449 }
3450
3451 //------------------------------build_loop_tree_impl---------------------------
3452 int PhaseIdealLoop::build_loop_tree_impl( Node *n, int pre_order ) {
3453 // ---- Post-pass Work ----
3454 // Pre-walked but not post-walked nodes need a pre_order number.
3455
3456 // Tightest enclosing loop for this Node
3457 IdealLoopTree *innermost = NULL;
3458
3459 // For all children, see if any edge is a backedge. If so, make a loop
3460 // for it. Then find the tightest enclosing loop for the self Node.
3461 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
3462 Node* m = n->fast_out(i); // Child
3463 if( n == m ) continue; // Ignore control self-cycles
3464 if( !m->is_CFG() ) continue;// Ignore non-CFG edges
3465
3466 IdealLoopTree *l; // Child's loop
3467 if( !is_postvisited(m) ) { // Child visited but not post-visited?
3468 // Found a backedge
3469 assert( get_preorder(m) < pre_order, "should be backedge" );
3470 // Check for the RootNode, which is already a LoopNode and is allowed
3471 // to have multiple "backedges".
3472 if( m == C->root()) { // Found the root?
3473 l = _ltree_root; // Root is the outermost LoopNode
3474 } else { // Else found a nested loop
3475 // Insert a LoopNode to mark this loop.
3476 l = new IdealLoopTree(this, m, n);
3477 } // End of Else found a nested loop
3478 if( !has_loop(m) ) // If 'm' does not already have a loop set
3479 set_loop(m, l); // Set loop header to loop now
3480
3481 } else { // Else not a nested loop
3482 if( !_nodes[m->_idx] ) continue; // Dead code has no loop
3483 l = get_loop(m); // Get previously determined loop
3484 // If successor is header of a loop (nest), move up-loop till it
3485 // is a member of some outer enclosing loop. Since there are no
3486 // shared headers (I've split them already) I only need to go up
3487 // at most 1 level.
3488 while( l && l->_head == m ) // Successor heads loop?
3489 l = l->_parent; // Move up 1 for me
3490 // If this loop is not properly parented, then this loop
3491 // has no exit path out, i.e. its an infinite loop.
3492 if( !l ) {
3493 // Make loop "reachable" from root so the CFG is reachable. Basically
3494 // insert a bogus loop exit that is never taken. 'm', the loop head,
3495 // points to 'n', one (of possibly many) fall-in paths. There may be
3496 // many backedges as well.
3497
3498 // Here I set the loop to be the root loop. I could have, after
3499 // inserting a bogus loop exit, restarted the recursion and found my
3500 // new loop exit. This would make the infinite loop a first-class
3501 // loop and it would then get properly optimized. What's the use of
3502 // optimizing an infinite loop?
3503 l = _ltree_root; // Oops, found infinite loop
3504
3505 if (!_verify_only) {
3506 // Insert the NeverBranch between 'm' and it's control user.
3507 NeverBranchNode *iff = new NeverBranchNode( m );
3508 _igvn.register_new_node_with_optimizer(iff);
3509 set_loop(iff, l);
3510 Node *if_t = new CProjNode( iff, 0 );
3511 _igvn.register_new_node_with_optimizer(if_t);
3512 set_loop(if_t, l);
3513
3514 Node* cfg = NULL; // Find the One True Control User of m
3515 for (DUIterator_Fast jmax, j = m->fast_outs(jmax); j < jmax; j++) {
3516 Node* x = m->fast_out(j);
3517 if (x->is_CFG() && x != m && x != iff)
3518 { cfg = x; break; }
3519 }
3520 assert(cfg != NULL, "must find the control user of m");
3521 uint k = 0; // Probably cfg->in(0)
3522 while( cfg->in(k) != m ) k++; // But check incase cfg is a Region
3523 cfg->set_req( k, if_t ); // Now point to NeverBranch
3524 _igvn._worklist.push(cfg);
3525
3526 // Now create the never-taken loop exit
3527 Node *if_f = new CProjNode( iff, 1 );
3528 _igvn.register_new_node_with_optimizer(if_f);
3529 set_loop(if_f, l);
3530 // Find frame ptr for Halt. Relies on the optimizer
3531 // V-N'ing. Easier and quicker than searching through
3532 // the program structure.
3533 Node *frame = new ParmNode( C->start(), TypeFunc::FramePtr );
3534 _igvn.register_new_node_with_optimizer(frame);
3535 // Halt & Catch Fire
3536 Node *halt = new HaltNode( if_f, frame );
3537 _igvn.register_new_node_with_optimizer(halt);
3538 set_loop(halt, l);
3539 C->root()->add_req(halt);
3540 }
3541 set_loop(C->root(), _ltree_root);
3542 }
3543 }
3544 // Weeny check for irreducible. This child was already visited (this
3545 // IS the post-work phase). Is this child's loop header post-visited
3546 // as well? If so, then I found another entry into the loop.
3547 if (!_verify_only) {
3548 while( is_postvisited(l->_head) ) {
3549 // found irreducible
3550 l->_irreducible = 1; // = true
3551 l = l->_parent;
3552 _has_irreducible_loops = true;
3553 // Check for bad CFG here to prevent crash, and bailout of compile
3554 if (l == NULL) {
3555 C->record_method_not_compilable("unhandled CFG detected during loop optimization");
3556 return pre_order;
3557 }
3558 }
3559 C->set_has_irreducible_loop(_has_irreducible_loops);
3560 }
3561
3562 // This Node might be a decision point for loops. It is only if
3563 // it's children belong to several different loops. The sort call
3564 // does a trivial amount of work if there is only 1 child or all
3565 // children belong to the same loop. If however, the children
3566 // belong to different loops, the sort call will properly set the
3567 // _parent pointers to show how the loops nest.
3568 //
3569 // In any case, it returns the tightest enclosing loop.
3570 innermost = sort( l, innermost );
3571 }
3572
3573 // Def-use info will have some dead stuff; dead stuff will have no
3574 // loop decided on.
3575
3576 // Am I a loop header? If so fix up my parent's child and next ptrs.
3577 if( innermost && innermost->_head == n ) {
3578 assert( get_loop(n) == innermost, "" );
3579 IdealLoopTree *p = innermost->_parent;
3580 IdealLoopTree *l = innermost;
3581 while( p && l->_head == n ) {
3582 l->_next = p->_child; // Put self on parents 'next child'
3583 p->_child = l; // Make self as first child of parent
3584 l = p; // Now walk up the parent chain
3585 p = l->_parent;
3586 }
3587 } else {
3588 // Note that it is possible for a LoopNode to reach here, if the
3589 // backedge has been made unreachable (hence the LoopNode no longer
3590 // denotes a Loop, and will eventually be removed).
3591
3592 // Record tightest enclosing loop for self. Mark as post-visited.
3593 set_loop(n, innermost);
3594 // Also record has_call flag early on
3595 if( innermost ) {
3596 if( n->is_Call() && !n->is_CallLeaf() && !n->is_macro() ) {
3597 // Do not count uncommon calls
3598 if( !n->is_CallStaticJava() || !n->as_CallStaticJava()->_name ) {
3599 Node *iff = n->in(0)->in(0);
3600 // No any calls for vectorized loops.
3601 if( UseSuperWord || !iff->is_If() ||
3602 (n->in(0)->Opcode() == Op_IfFalse &&
3603 (1.0 - iff->as_If()->_prob) >= 0.01) ||
3604 (iff->as_If()->_prob >= 0.01) )
3605 innermost->_has_call = 1;
3606 }
3607 } else if( n->is_Allocate() && n->as_Allocate()->_is_scalar_replaceable ) {
3608 // Disable loop optimizations if the loop has a scalar replaceable
3609 // allocation. This disabling may cause a potential performance lost
3610 // if the allocation is not eliminated for some reason.
3611 innermost->_allow_optimizations = false;
3612 innermost->_has_call = 1; // = true
3613 } else if (n->Opcode() == Op_SafePoint) {
3614 // Record all safepoints in this loop.
3615 if (innermost->_safepts == NULL) innermost->_safepts = new Node_List();
3616 innermost->_safepts->push(n);
3617 }
3618 }
3619 }
3620
3621 // Flag as post-visited now
3622 set_postvisited(n);
3623 return pre_order;
3624 }
3625
3626
3627 //------------------------------build_loop_early-------------------------------
3628 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
3629 // First pass computes the earliest controlling node possible. This is the
3630 // controlling input with the deepest dominating depth.
3631 void PhaseIdealLoop::build_loop_early( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
3632 while (worklist.size() != 0) {
3633 // Use local variables nstack_top_n & nstack_top_i to cache values
3634 // on nstack's top.
3635 Node *nstack_top_n = worklist.pop();
3636 uint nstack_top_i = 0;
3637 //while_nstack_nonempty:
3638 while (true) {
3639 // Get parent node and next input's index from stack's top.
3640 Node *n = nstack_top_n;
3641 uint i = nstack_top_i;
3642 uint cnt = n->req(); // Count of inputs
3643 if (i == 0) { // Pre-process the node.
3644 if( has_node(n) && // Have either loop or control already?
3645 !has_ctrl(n) ) { // Have loop picked out already?
3646 // During "merge_many_backedges" we fold up several nested loops
3647 // into a single loop. This makes the members of the original
3648 // loop bodies pointing to dead loops; they need to move up
3649 // to the new UNION'd larger loop. I set the _head field of these
3650 // dead loops to NULL and the _parent field points to the owning
3651 // loop. Shades of UNION-FIND algorithm.
3652 IdealLoopTree *ilt;
3653 while( !(ilt = get_loop(n))->_head ) {
3654 // Normally I would use a set_loop here. But in this one special
3655 // case, it is legal (and expected) to change what loop a Node
3656 // belongs to.
3657 _nodes.map(n->_idx, (Node*)(ilt->_parent) );
3658 }
3659 // Remove safepoints ONLY if I've already seen I don't need one.
3660 // (the old code here would yank a 2nd safepoint after seeing a
3661 // first one, even though the 1st did not dominate in the loop body
3662 // and thus could be avoided indefinitely)
3663 if( !_verify_only && !_verify_me && ilt->_has_sfpt && n->Opcode() == Op_SafePoint &&
3664 is_deleteable_safept(n)) {
3665 Node *in = n->in(TypeFunc::Control);
3666 lazy_replace(n,in); // Pull safepoint now
3667 if (ilt->_safepts != NULL) {
3668 ilt->_safepts->yank(n);
3669 }
3670 // Carry on with the recursion "as if" we are walking
3671 // only the control input
3672 if( !visited.test_set( in->_idx ) ) {
3673 worklist.push(in); // Visit this guy later, using worklist
3674 }
3675 // Get next node from nstack:
3676 // - skip n's inputs processing by setting i > cnt;
3677 // - we also will not call set_early_ctrl(n) since
3678 // has_node(n) == true (see the condition above).
3679 i = cnt + 1;
3680 }
3681 }
3682 } // if (i == 0)
3683
3684 // Visit all inputs
3685 bool done = true; // Assume all n's inputs will be processed
3686 while (i < cnt) {
3687 Node *in = n->in(i);
3688 ++i;
3689 if (in == NULL) continue;
3690 if (in->pinned() && !in->is_CFG())
3691 set_ctrl(in, in->in(0));
3692 int is_visited = visited.test_set( in->_idx );
3693 if (!has_node(in)) { // No controlling input yet?
3694 assert( !in->is_CFG(), "CFG Node with no controlling input?" );
3695 assert( !is_visited, "visit only once" );
3696 nstack.push(n, i); // Save parent node and next input's index.
3697 nstack_top_n = in; // Process current input now.
3698 nstack_top_i = 0;
3699 done = false; // Not all n's inputs processed.
3700 break; // continue while_nstack_nonempty;
3701 } else if (!is_visited) {
3702 // This guy has a location picked out for him, but has not yet
3703 // been visited. Happens to all CFG nodes, for instance.
3704 // Visit him using the worklist instead of recursion, to break
3705 // cycles. Since he has a location already we do not need to
3706 // find his location before proceeding with the current Node.
3707 worklist.push(in); // Visit this guy later, using worklist
3708 }
3709 }
3710 if (done) {
3711 // All of n's inputs have been processed, complete post-processing.
3712
3713 // Compute earliest point this Node can go.
3714 // CFG, Phi, pinned nodes already know their controlling input.
3715 if (!has_node(n)) {
3716 // Record earliest legal location
3717 set_early_ctrl( n );
3718 }
3719 if (nstack.is_empty()) {
3720 // Finished all nodes on stack.
3721 // Process next node on the worklist.
3722 break;
3723 }
3724 // Get saved parent node and next input's index.
3725 nstack_top_n = nstack.node();
3726 nstack_top_i = nstack.index();
3727 nstack.pop();
3728 }
3729 } // while (true)
3730 }
3731 }
3732
3733 //------------------------------dom_lca_internal--------------------------------
3734 // Pair-wise LCA
3735 Node *PhaseIdealLoop::dom_lca_internal( Node *n1, Node *n2 ) const {
3736 if( !n1 ) return n2; // Handle NULL original LCA
3737 assert( n1->is_CFG(), "" );
3738 assert( n2->is_CFG(), "" );
3739 // find LCA of all uses
3740 uint d1 = dom_depth(n1);
3741 uint d2 = dom_depth(n2);
3742 while (n1 != n2) {
3743 if (d1 > d2) {
3744 n1 = idom(n1);
3745 d1 = dom_depth(n1);
3746 } else if (d1 < d2) {
3747 n2 = idom(n2);
3748 d2 = dom_depth(n2);
3749 } else {
3750 // Here d1 == d2. Due to edits of the dominator-tree, sections
3751 // of the tree might have the same depth. These sections have
3752 // to be searched more carefully.
3753
3754 // Scan up all the n1's with equal depth, looking for n2.
3755 Node *t1 = idom(n1);
3756 while (dom_depth(t1) == d1) {
3757 if (t1 == n2) return n2;
3758 t1 = idom(t1);
3759 }
3760 // Scan up all the n2's with equal depth, looking for n1.
3761 Node *t2 = idom(n2);
3762 while (dom_depth(t2) == d2) {
3763 if (t2 == n1) return n1;
3764 t2 = idom(t2);
3765 }
3766 // Move up to a new dominator-depth value as well as up the dom-tree.
3767 n1 = t1;
3768 n2 = t2;
3769 d1 = dom_depth(n1);
3770 d2 = dom_depth(n2);
3771 }
3772 }
3773 return n1;
3774 }
3775
3776 //------------------------------compute_idom-----------------------------------
3777 // Locally compute IDOM using dom_lca call. Correct only if the incoming
3778 // IDOMs are correct.
3779 Node *PhaseIdealLoop::compute_idom( Node *region ) const {
3780 assert( region->is_Region(), "" );
3781 Node *LCA = NULL;
3782 for( uint i = 1; i < region->req(); i++ ) {
3783 if( region->in(i) != C->top() )
3784 LCA = dom_lca( LCA, region->in(i) );
3785 }
3786 return LCA;
3787 }
3788
3789 bool PhaseIdealLoop::verify_dominance(Node* n, Node* use, Node* LCA, Node* early) {
3790 bool had_error = false;
3791 #ifdef ASSERT
3792 if (early != C->root()) {
3793 // Make sure that there's a dominance path from LCA to early
3794 Node* d = LCA;
3795 while (d != early) {
3796 if (d == C->root()) {
3797 dump_bad_graph("Bad graph detected in compute_lca_of_uses", n, early, LCA);
3798 tty->print_cr("*** Use %d isn't dominated by def %d ***", use->_idx, n->_idx);
3799 had_error = true;
3800 break;
3801 }
3802 d = idom(d);
3803 }
3804 }
3805 #endif
3806 return had_error;
3807 }
3808
3809
3810 Node* PhaseIdealLoop::compute_lca_of_uses(Node* n, Node* early, bool verify) {
3811 // Compute LCA over list of uses
3812 bool had_error = false;
3813 Node *LCA = NULL;
3814 for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax && LCA != early; i++) {
3815 Node* c = n->fast_out(i);
3816 if (_nodes[c->_idx] == NULL)
3817 continue; // Skip the occasional dead node
3818 if( c->is_Phi() ) { // For Phis, we must land above on the path
3819 for( uint j=1; j<c->req(); j++ ) {// For all inputs
3820 if( c->in(j) == n ) { // Found matching input?
3821 Node *use = c->in(0)->in(j);
3822 if (_verify_only && use->is_top()) continue;
3823 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
3824 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
3825 }
3826 }
3827 } else {
3828 // For CFG data-users, use is in the block just prior
3829 Node *use = has_ctrl(c) ? get_ctrl(c) : c->in(0);
3830 LCA = dom_lca_for_get_late_ctrl( LCA, use, n );
3831 if (verify) had_error = verify_dominance(n, use, LCA, early) || had_error;
3832 }
3833 }
3834 assert(!had_error, "bad dominance");
3835 return LCA;
3836 }
3837
3838 // Check the shape of the graph at the loop entry. In some cases,
3839 // the shape of the graph does not match the shape outlined below.
3840 // That is caused by the Opaque1 node "protecting" the shape of
3841 // the graph being removed by, for example, the IGVN performed
3842 // in PhaseIdealLoop::build_and_optimize().
3843 //
3844 // After the Opaque1 node has been removed, optimizations (e.g., split-if,
3845 // loop unswitching, and IGVN, or a combination of them) can freely change
3846 // the graph's shape. As a result, the graph shape outlined below cannot
3847 // be guaranteed anymore.
3848 bool PhaseIdealLoop::is_canonical_loop_entry(CountedLoopNode* cl) {
3849 if (!cl->is_main_loop() && !cl->is_post_loop()) {
3850 return false;
3851 }
3852 Node* ctrl = cl->skip_predicates();
3853
3854 if (ctrl == NULL || (!ctrl->is_IfTrue() && !ctrl->is_IfFalse())) {
3855 return false;
3856 }
3857 Node* iffm = ctrl->in(0);
3858 if (iffm == NULL || !iffm->is_If()) {
3859 return false;
3860 }
3861 Node* bolzm = iffm->in(1);
3862 if (bolzm == NULL || !bolzm->is_Bool()) {
3863 return false;
3864 }
3865 Node* cmpzm = bolzm->in(1);
3866 if (cmpzm == NULL || !cmpzm->is_Cmp()) {
3867 return false;
3868 }
3869 // compares can get conditionally flipped
3870 bool found_opaque = false;
3871 for (uint i = 1; i < cmpzm->req(); i++) {
3872 Node* opnd = cmpzm->in(i);
3873 if (opnd && opnd->Opcode() == Op_Opaque1) {
3874 found_opaque = true;
3875 break;
3876 }
3877 }
3878 if (!found_opaque) {
3879 return false;
3880 }
3881 return true;
3882 }
3883
3884 //------------------------------get_late_ctrl----------------------------------
3885 // Compute latest legal control.
3886 Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
3887 assert(early != NULL, "early control should not be NULL");
3888
3889 Node* LCA = compute_lca_of_uses(n, early);
3890 #ifdef ASSERT
3891 if (LCA == C->root() && LCA != early) {
3892 // def doesn't dominate uses so print some useful debugging output
3893 compute_lca_of_uses(n, early, true);
3894 }
3895 #endif
3896
3897 // if this is a load, check for anti-dependent stores
3898 // We use a conservative algorithm to identify potential interfering
3899 // instructions and for rescheduling the load. The users of the memory
3900 // input of this load are examined. Any use which is not a load and is
3901 // dominated by early is considered a potentially interfering store.
3902 // This can produce false positives.
3903 if (n->is_Load() && LCA != early) {
3904 Node_List worklist;
3905
3906 Node *mem = n->in(MemNode::Memory);
3907 for (DUIterator_Fast imax, i = mem->fast_outs(imax); i < imax; i++) {
3908 Node* s = mem->fast_out(i);
3909 worklist.push(s);
3910 }
3911 while(worklist.size() != 0 && LCA != early) {
3912 Node* s = worklist.pop();
3913 if (s->is_Load() || s->Opcode() == Op_SafePoint) {
3914 continue;
3915 } else if (s->is_MergeMem()) {
3916 for (DUIterator_Fast imax, i = s->fast_outs(imax); i < imax; i++) {
3917 Node* s1 = s->fast_out(i);
3918 worklist.push(s1);
3919 }
3920 } else {
3921 Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0);
3922 assert(sctrl != NULL || s->outcnt() == 0, "must have control");
3923 if (sctrl != NULL && !sctrl->is_top() && is_dominator(early, sctrl)) {
3924 LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
3925 }
3926 }
3927 }
3928 }
3929
3930 assert(LCA == find_non_split_ctrl(LCA), "unexpected late control");
3931 return LCA;
3932 }
3933
3934 // true if CFG node d dominates CFG node n
3935 bool PhaseIdealLoop::is_dominator(Node *d, Node *n) {
3936 if (d == n)
3937 return true;
3938 assert(d->is_CFG() && n->is_CFG(), "must have CFG nodes");
3939 uint dd = dom_depth(d);
3940 while (dom_depth(n) >= dd) {
3941 if (n == d)
3942 return true;
3943 n = idom(n);
3944 }
3945 return false;
3946 }
3947
3948 //------------------------------dom_lca_for_get_late_ctrl_internal-------------
3949 // Pair-wise LCA with tags.
3950 // Tag each index with the node 'tag' currently being processed
3951 // before advancing up the dominator chain using idom().
3952 // Later calls that find a match to 'tag' know that this path has already
3953 // been considered in the current LCA (which is input 'n1' by convention).
3954 // Since get_late_ctrl() is only called once for each node, the tag array
3955 // does not need to be cleared between calls to get_late_ctrl().
3956 // Algorithm trades a larger constant factor for better asymptotic behavior
3957 //
3958 Node *PhaseIdealLoop::dom_lca_for_get_late_ctrl_internal( Node *n1, Node *n2, Node *tag ) {
3959 uint d1 = dom_depth(n1);
3960 uint d2 = dom_depth(n2);
3961
3962 do {
3963 if (d1 > d2) {
3964 // current lca is deeper than n2
3965 _dom_lca_tags.map(n1->_idx, tag);
3966 n1 = idom(n1);
3967 d1 = dom_depth(n1);
3968 } else if (d1 < d2) {
3969 // n2 is deeper than current lca
3970 Node *memo = _dom_lca_tags[n2->_idx];
3971 if( memo == tag ) {
3972 return n1; // Return the current LCA
3973 }
3974 _dom_lca_tags.map(n2->_idx, tag);
3975 n2 = idom(n2);
3976 d2 = dom_depth(n2);
3977 } else {
3978 // Here d1 == d2. Due to edits of the dominator-tree, sections
3979 // of the tree might have the same depth. These sections have
3980 // to be searched more carefully.
3981
3982 // Scan up all the n1's with equal depth, looking for n2.
3983 _dom_lca_tags.map(n1->_idx, tag);
3984 Node *t1 = idom(n1);
3985 while (dom_depth(t1) == d1) {
3986 if (t1 == n2) return n2;
3987 _dom_lca_tags.map(t1->_idx, tag);
3988 t1 = idom(t1);
3989 }
3990 // Scan up all the n2's with equal depth, looking for n1.
3991 _dom_lca_tags.map(n2->_idx, tag);
3992 Node *t2 = idom(n2);
3993 while (dom_depth(t2) == d2) {
3994 if (t2 == n1) return n1;
3995 _dom_lca_tags.map(t2->_idx, tag);
3996 t2 = idom(t2);
3997 }
3998 // Move up to a new dominator-depth value as well as up the dom-tree.
3999 n1 = t1;
4000 n2 = t2;
4001 d1 = dom_depth(n1);
4002 d2 = dom_depth(n2);
4003 }
4004 } while (n1 != n2);
4005 return n1;
4006 }
4007
4008 //------------------------------init_dom_lca_tags------------------------------
4009 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
4010 // Intended use does not involve any growth for the array, so it could
4011 // be of fixed size.
4012 void PhaseIdealLoop::init_dom_lca_tags() {
4013 uint limit = C->unique() + 1;
4014 _dom_lca_tags.map( limit, NULL );
4015 #ifdef ASSERT
4016 for( uint i = 0; i < limit; ++i ) {
4017 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
4018 }
4019 #endif // ASSERT
4020 }
4021
4022 //------------------------------clear_dom_lca_tags------------------------------
4023 // Tag could be a node's integer index, 32bits instead of 64bits in some cases
4024 // Intended use does not involve any growth for the array, so it could
4025 // be of fixed size.
4026 void PhaseIdealLoop::clear_dom_lca_tags() {
4027 uint limit = C->unique() + 1;
4028 _dom_lca_tags.map( limit, NULL );
4029 _dom_lca_tags.clear();
4030 #ifdef ASSERT
4031 for( uint i = 0; i < limit; ++i ) {
4032 assert(_dom_lca_tags[i] == NULL, "Must be distinct from each node pointer");
4033 }
4034 #endif // ASSERT
4035 }
4036
4037 //------------------------------build_loop_late--------------------------------
4038 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
4039 // Second pass finds latest legal placement, and ideal loop placement.
4040 void PhaseIdealLoop::build_loop_late( VectorSet &visited, Node_List &worklist, Node_Stack &nstack ) {
4041 while (worklist.size() != 0) {
4042 Node *n = worklist.pop();
4043 // Only visit once
4044 if (visited.test_set(n->_idx)) continue;
4045 uint cnt = n->outcnt();
4046 uint i = 0;
4047 while (true) {
4048 assert( _nodes[n->_idx], "no dead nodes" );
4049 // Visit all children
4050 if (i < cnt) {
4051 Node* use = n->raw_out(i);
4052 ++i;
4053 // Check for dead uses. Aggressively prune such junk. It might be
4054 // dead in the global sense, but still have local uses so I cannot
4055 // easily call 'remove_dead_node'.
4056 if( _nodes[use->_idx] != NULL || use->is_top() ) { // Not dead?
4057 // Due to cycles, we might not hit the same fixed point in the verify
4058 // pass as we do in the regular pass. Instead, visit such phis as
4059 // simple uses of the loop head.
4060 if( use->in(0) && (use->is_CFG() || use->is_Phi()) ) {
4061 if( !visited.test(use->_idx) )
4062 worklist.push(use);
4063 } else if( !visited.test_set(use->_idx) ) {
4064 nstack.push(n, i); // Save parent and next use's index.
4065 n = use; // Process all children of current use.
4066 cnt = use->outcnt();
4067 i = 0;
4068 }
4069 } else {
4070 // Do not visit around the backedge of loops via data edges.
4071 // push dead code onto a worklist
4072 _deadlist.push(use);
4073 }
4074 } else {
4075 // All of n's children have been processed, complete post-processing.
4076 build_loop_late_post(n);
4077 if (nstack.is_empty()) {
4078 // Finished all nodes on stack.
4079 // Process next node on the worklist.
4080 break;
4081 }
4082 // Get saved parent node and next use's index. Visit the rest of uses.
4083 n = nstack.node();
4084 cnt = n->outcnt();
4085 i = nstack.index();
4086 nstack.pop();
4087 }
4088 }
4089 }
4090 }
4091
4092 // Verify that no data node is schedules in the outer loop of a strip
4093 // mined loop.
4094 void PhaseIdealLoop::verify_strip_mined_scheduling(Node *n, Node* least) {
4095 #ifdef ASSERT
4096 if (get_loop(least)->_nest == 0) {
4097 return;
4098 }
4099 IdealLoopTree* loop = get_loop(least);
4100 Node* head = loop->_head;
4101 if (head->is_OuterStripMinedLoop()) {
4102 Node* sfpt = head->as_Loop()->outer_safepoint();
4103 ResourceMark rm;
4104 Unique_Node_List wq;
4105 wq.push(sfpt);
4106 for (uint i = 0; i < wq.size(); i++) {
4107 Node *m = wq.at(i);
4108 for (uint i = 1; i < m->req(); i++) {
4109 Node* nn = m->in(i);
4110 if (nn == n) {
4111 return;
4112 }
4113 if (nn != NULL && has_ctrl(nn) && get_loop(get_ctrl(nn)) == loop) {
4114 wq.push(nn);
4115 }
4116 }
4117 }
4118 ShouldNotReachHere();
4119 }
4120 #endif
4121 }
4122
4123
4124 //------------------------------build_loop_late_post---------------------------
4125 // Put Data nodes into some loop nest, by setting the _nodes[]->loop mapping.
4126 // Second pass finds latest legal placement, and ideal loop placement.
4127 void PhaseIdealLoop::build_loop_late_post( Node *n ) {
4128
4129 if (n->req() == 2 && (n->Opcode() == Op_ConvI2L || n->Opcode() == Op_CastII) && !C->major_progress() && !_verify_only) {
4130 _igvn._worklist.push(n); // Maybe we'll normalize it, if no more loops.
4131 }
4132
4133 #ifdef ASSERT
4134 if (_verify_only && !n->is_CFG()) {
4135 // Check def-use domination.
4136 compute_lca_of_uses(n, get_ctrl(n), true /* verify */);
4137 }
4138 #endif
4139
4140 // CFG and pinned nodes already handled
4141 if( n->in(0) ) {
4142 if( n->in(0)->is_top() ) return; // Dead?
4143
4144 // We'd like +VerifyLoopOptimizations to not believe that Mod's/Loads
4145 // _must_ be pinned (they have to observe their control edge of course).
4146 // Unlike Stores (which modify an unallocable resource, the memory
4147 // state), Mods/Loads can float around. So free them up.
4148 bool pinned = true;
4149 switch( n->Opcode() ) {
4150 case Op_DivI:
4151 case Op_DivF:
4152 case Op_DivD:
4153 case Op_ModI:
4154 case Op_ModF:
4155 case Op_ModD:
4156 case Op_LoadB: // Same with Loads; they can sink
4157 case Op_LoadUB: // during loop optimizations.
4158 case Op_LoadUS:
4159 case Op_LoadD:
4160 case Op_LoadF:
4161 case Op_LoadI:
4162 case Op_LoadKlass:
4163 case Op_LoadNKlass:
4164 case Op_LoadL:
4165 case Op_LoadS:
4166 case Op_LoadP:
4167 case Op_LoadBarrierSlowReg:
4168 case Op_LoadBarrierWeakSlowReg:
4169 case Op_LoadN:
4170 case Op_LoadRange:
4171 case Op_LoadD_unaligned:
4172 case Op_LoadL_unaligned:
4173 case Op_StrComp: // Does a bunch of load-like effects
4174 case Op_StrEquals:
4175 case Op_StrIndexOf:
4176 case Op_StrIndexOfChar:
4177 case Op_AryEq:
4178 case Op_HasNegatives:
4179 pinned = false;
4180 }
4181 if( pinned ) {
4182 IdealLoopTree *chosen_loop = get_loop(n->is_CFG() ? n : get_ctrl(n));
4183 if( !chosen_loop->_child ) // Inner loop?
4184 chosen_loop->_body.push(n); // Collect inner loops
4185 return;
4186 }
4187 } else { // No slot zero
4188 if( n->is_CFG() ) { // CFG with no slot 0 is dead
4189 _nodes.map(n->_idx,0); // No block setting, it's globally dead
4190 return;
4191 }
4192 assert(!n->is_CFG() || n->outcnt() == 0, "");
4193 }
4194
4195 // Do I have a "safe range" I can select over?
4196 Node *early = get_ctrl(n);// Early location already computed
4197
4198 // Compute latest point this Node can go
4199 Node *LCA = get_late_ctrl( n, early );
4200 // LCA is NULL due to uses being dead
4201 if( LCA == NULL ) {
4202 #ifdef ASSERT
4203 for (DUIterator i1 = n->outs(); n->has_out(i1); i1++) {
4204 assert( _nodes[n->out(i1)->_idx] == NULL, "all uses must also be dead");
4205 }
4206 #endif
4207 _nodes.map(n->_idx, 0); // This node is useless
4208 _deadlist.push(n);
4209 return;
4210 }
4211 assert(LCA != NULL && !LCA->is_top(), "no dead nodes");
4212
4213 Node *legal = LCA; // Walk 'legal' up the IDOM chain
4214 Node *least = legal; // Best legal position so far
4215 while( early != legal ) { // While not at earliest legal
4216 #ifdef ASSERT
4217 if (legal->is_Start() && !early->is_Root()) {
4218 // Bad graph. Print idom path and fail.
4219 dump_bad_graph("Bad graph detected in build_loop_late", n, early, LCA);
4220 assert(false, "Bad graph detected in build_loop_late");
4221 }
4222 #endif
4223 // Find least loop nesting depth
4224 legal = idom(legal); // Bump up the IDOM tree
4225 // Check for lower nesting depth
4226 if( get_loop(legal)->_nest < get_loop(least)->_nest )
4227 least = legal;
4228 }
4229 assert(early == legal || legal != C->root(), "bad dominance of inputs");
4230
4231 // Try not to place code on a loop entry projection
4232 // which can inhibit range check elimination.
4233 if (least != early) {
4234 Node* ctrl_out = least->unique_ctrl_out();
4235 if (ctrl_out && ctrl_out->is_Loop() &&
4236 least == ctrl_out->in(LoopNode::EntryControl)) {
4237 // Move the node above predicates as far up as possible so a
4238 // following pass of loop predication doesn't hoist a predicate
4239 // that depends on it above that node.
4240 Node* new_ctrl = least;
4241 for (;;) {
4242 if (!new_ctrl->is_Proj()) {
4243 break;
4244 }
4245 CallStaticJavaNode* call = new_ctrl->as_Proj()->is_uncommon_trap_if_pattern(Deoptimization::Reason_none);
4246 if (call == NULL) {
4247 break;
4248 }
4249 int req = call->uncommon_trap_request();
4250 Deoptimization::DeoptReason trap_reason = Deoptimization::trap_request_reason(req);
4251 if (trap_reason != Deoptimization::Reason_loop_limit_check &&
4252 trap_reason != Deoptimization::Reason_predicate &&
4253 trap_reason != Deoptimization::Reason_profile_predicate) {
4254 break;
4255 }
4256 Node* c = new_ctrl->in(0)->in(0);
4257 if (is_dominator(c, early) && c != early) {
4258 break;
4259 }
4260 new_ctrl = c;
4261 }
4262 least = new_ctrl;
4263 }
4264 }
4265
4266 #ifdef ASSERT
4267 // If verifying, verify that 'verify_me' has a legal location
4268 // and choose it as our location.
4269 if( _verify_me ) {
4270 Node *v_ctrl = _verify_me->get_ctrl_no_update(n);
4271 Node *legal = LCA;
4272 while( early != legal ) { // While not at earliest legal
4273 if( legal == v_ctrl ) break; // Check for prior good location
4274 legal = idom(legal) ;// Bump up the IDOM tree
4275 }
4276 // Check for prior good location
4277 if( legal == v_ctrl ) least = legal; // Keep prior if found
4278 }
4279 #endif
4280
4281 // Assign discovered "here or above" point
4282 least = find_non_split_ctrl(least);
4283 verify_strip_mined_scheduling(n, least);
4284 set_ctrl(n, least);
4285
4286 // Collect inner loop bodies
4287 IdealLoopTree *chosen_loop = get_loop(least);
4288 if( !chosen_loop->_child ) // Inner loop?
4289 chosen_loop->_body.push(n);// Collect inner loops
4290 }
4291
4292 #ifdef ASSERT
4293 void PhaseIdealLoop::dump_bad_graph(const char* msg, Node* n, Node* early, Node* LCA) {
4294 tty->print_cr("%s", msg);
4295 tty->print("n: "); n->dump();
4296 tty->print("early(n): "); early->dump();
4297 if (n->in(0) != NULL && !n->in(0)->is_top() &&
4298 n->in(0) != early && !n->in(0)->is_Root()) {
4299 tty->print("n->in(0): "); n->in(0)->dump();
4300 }
4301 for (uint i = 1; i < n->req(); i++) {
4302 Node* in1 = n->in(i);
4303 if (in1 != NULL && in1 != n && !in1->is_top()) {
4304 tty->print("n->in(%d): ", i); in1->dump();
4305 Node* in1_early = get_ctrl(in1);
4306 tty->print("early(n->in(%d)): ", i); in1_early->dump();
4307 if (in1->in(0) != NULL && !in1->in(0)->is_top() &&
4308 in1->in(0) != in1_early && !in1->in(0)->is_Root()) {
4309 tty->print("n->in(%d)->in(0): ", i); in1->in(0)->dump();
4310 }
4311 for (uint j = 1; j < in1->req(); j++) {
4312 Node* in2 = in1->in(j);
4313 if (in2 != NULL && in2 != n && in2 != in1 && !in2->is_top()) {
4314 tty->print("n->in(%d)->in(%d): ", i, j); in2->dump();
4315 Node* in2_early = get_ctrl(in2);
4316 tty->print("early(n->in(%d)->in(%d)): ", i, j); in2_early->dump();
4317 if (in2->in(0) != NULL && !in2->in(0)->is_top() &&
4318 in2->in(0) != in2_early && !in2->in(0)->is_Root()) {
4319 tty->print("n->in(%d)->in(%d)->in(0): ", i, j); in2->in(0)->dump();
4320 }
4321 }
4322 }
4323 }
4324 }
4325 tty->cr();
4326 tty->print("LCA(n): "); LCA->dump();
4327 for (uint i = 0; i < n->outcnt(); i++) {
4328 Node* u1 = n->raw_out(i);
4329 if (u1 == n)
4330 continue;
4331 tty->print("n->out(%d): ", i); u1->dump();
4332 if (u1->is_CFG()) {
4333 for (uint j = 0; j < u1->outcnt(); j++) {
4334 Node* u2 = u1->raw_out(j);
4335 if (u2 != u1 && u2 != n && u2->is_CFG()) {
4336 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
4337 }
4338 }
4339 } else {
4340 Node* u1_later = get_ctrl(u1);
4341 tty->print("later(n->out(%d)): ", i); u1_later->dump();
4342 if (u1->in(0) != NULL && !u1->in(0)->is_top() &&
4343 u1->in(0) != u1_later && !u1->in(0)->is_Root()) {
4344 tty->print("n->out(%d)->in(0): ", i); u1->in(0)->dump();
4345 }
4346 for (uint j = 0; j < u1->outcnt(); j++) {
4347 Node* u2 = u1->raw_out(j);
4348 if (u2 == n || u2 == u1)
4349 continue;
4350 tty->print("n->out(%d)->out(%d): ", i, j); u2->dump();
4351 if (!u2->is_CFG()) {
4352 Node* u2_later = get_ctrl(u2);
4353 tty->print("later(n->out(%d)->out(%d)): ", i, j); u2_later->dump();
4354 if (u2->in(0) != NULL && !u2->in(0)->is_top() &&
4355 u2->in(0) != u2_later && !u2->in(0)->is_Root()) {
4356 tty->print("n->out(%d)->in(0): ", i); u2->in(0)->dump();
4357 }
4358 }
4359 }
4360 }
4361 }
4362 tty->cr();
4363 int ct = 0;
4364 Node *dbg_legal = LCA;
4365 while(!dbg_legal->is_Start() && ct < 100) {
4366 tty->print("idom[%d] ",ct); dbg_legal->dump();
4367 ct++;
4368 dbg_legal = idom(dbg_legal);
4369 }
4370 tty->cr();
4371 }
4372 #endif
4373
4374 #ifndef PRODUCT
4375 //------------------------------dump-------------------------------------------
4376 void PhaseIdealLoop::dump( ) const {
4377 ResourceMark rm;
4378 Arena* arena = Thread::current()->resource_area();
4379 Node_Stack stack(arena, C->live_nodes() >> 2);
4380 Node_List rpo_list;
4381 VectorSet visited(arena);
4382 visited.set(C->top()->_idx);
4383 rpo( C->root(), stack, visited, rpo_list );
4384 // Dump root loop indexed by last element in PO order
4385 dump( _ltree_root, rpo_list.size(), rpo_list );
4386 }
4387
4388 void PhaseIdealLoop::dump( IdealLoopTree *loop, uint idx, Node_List &rpo_list ) const {
4389 loop->dump_head();
4390
4391 // Now scan for CFG nodes in the same loop
4392 for( uint j=idx; j > 0; j-- ) {
4393 Node *n = rpo_list[j-1];
4394 if( !_nodes[n->_idx] ) // Skip dead nodes
4395 continue;
4396 if( get_loop(n) != loop ) { // Wrong loop nest
4397 if( get_loop(n)->_head == n && // Found nested loop?
4398 get_loop(n)->_parent == loop )
4399 dump(get_loop(n),rpo_list.size(),rpo_list); // Print it nested-ly
4400 continue;
4401 }
4402
4403 // Dump controlling node
4404 for( uint x = 0; x < loop->_nest; x++ )
4405 tty->print(" ");
4406 tty->print("C");
4407 if( n == C->root() ) {
4408 n->dump();
4409 } else {
4410 Node* cached_idom = idom_no_update(n);
4411 Node *computed_idom = n->in(0);
4412 if( n->is_Region() ) {
4413 computed_idom = compute_idom(n);
4414 // computed_idom() will return n->in(0) when idom(n) is an IfNode (or
4415 // any MultiBranch ctrl node), so apply a similar transform to
4416 // the cached idom returned from idom_no_update.
4417 cached_idom = find_non_split_ctrl(cached_idom);
4418 }
4419 tty->print(" ID:%d",computed_idom->_idx);
4420 n->dump();
4421 if( cached_idom != computed_idom ) {
4422 tty->print_cr("*** BROKEN IDOM! Computed as: %d, cached as: %d",
4423 computed_idom->_idx, cached_idom->_idx);
4424 }
4425 }
4426 // Dump nodes it controls
4427 for( uint k = 0; k < _nodes.Size(); k++ ) {
4428 // (k < C->unique() && get_ctrl(find(k)) == n)
4429 if (k < C->unique() && _nodes[k] == (Node*)((intptr_t)n + 1)) {
4430 Node *m = C->root()->find(k);
4431 if( m && m->outcnt() > 0 ) {
4432 if (!(has_ctrl(m) && get_ctrl_no_update(m) == n)) {
4433 tty->print_cr("*** BROKEN CTRL ACCESSOR! _nodes[k] is %p, ctrl is %p",
4434 _nodes[k], has_ctrl(m) ? get_ctrl_no_update(m) : NULL);
4435 }
4436 for( uint j = 0; j < loop->_nest; j++ )
4437 tty->print(" ");
4438 tty->print(" ");
4439 m->dump();
4440 }
4441 }
4442 }
4443 }
4444 }
4445
4446 // Collect a R-P-O for the whole CFG.
4447 // Result list is in post-order (scan backwards for RPO)
4448 void PhaseIdealLoop::rpo( Node *start, Node_Stack &stk, VectorSet &visited, Node_List &rpo_list ) const {
4449 stk.push(start, 0);
4450 visited.set(start->_idx);
4451
4452 while (stk.is_nonempty()) {
4453 Node* m = stk.node();
4454 uint idx = stk.index();
4455 if (idx < m->outcnt()) {
4456 stk.set_index(idx + 1);
4457 Node* n = m->raw_out(idx);
4458 if (n->is_CFG() && !visited.test_set(n->_idx)) {
4459 stk.push(n, 0);
4460 }
4461 } else {
4462 rpo_list.push(m);
4463 stk.pop();
4464 }
4465 }
4466 }
4467 #endif
4468
4469
4470 //=============================================================================
4471 //------------------------------LoopTreeIterator-----------------------------------
4472
4473 // Advance to next loop tree using a preorder, left-to-right traversal.
4474 void LoopTreeIterator::next() {
4475 assert(!done(), "must not be done.");
4476 if (_curnt->_child != NULL) {
4477 _curnt = _curnt->_child;
4478 } else if (_curnt->_next != NULL) {
4479 _curnt = _curnt->_next;
4480 } else {
4481 while (_curnt != _root && _curnt->_next == NULL) {
4482 _curnt = _curnt->_parent;
4483 }
4484 if (_curnt == _root) {
4485 _curnt = NULL;
4486 assert(done(), "must be done.");
4487 } else {
4488 assert(_curnt->_next != NULL, "must be more to do");
4489 _curnt = _curnt->_next;
4490 }
4491 }
4492 }